MATH HELP !!!! i Cant seem to get these 4 Questions.?

Question

19.
Substitution would be the simplest method of solution for which system?
(Points : 2)

A. 5/3 x = 6y and 2x -3y = 8


B. y = 2x and x + y = 28


C. 3x - 2y =18 and 4x + 5y =60


20.
The sum of two numbers is 110. Their difference is 28. What is the smallest of the two numbers?
(Points : 2)

A. 56


B. 41


C. 69


D. 55


21.
If I buy two apples and six oranges, I will spend $5.60. However, if I buy six apples and two oranges, I will spend $4.80. How much does one orange cost?
(Points : 2)

A. $0.55


B. $0.70


C. $0.75


D. $0.60


22.
Choose all correct answers. Which of the following ordered pairs are solutions of the system, y > 3 and y < 2x + 2?
(Points : 2)

A. (0 , 2)


B. (2, 4)


C. (3, 5)


D. (-2, 0)

Answer 1

for the first one the answer is B because it looks plainly clear that the substitution is already made for you with "y=2x".



for question 2 lets solve it!

let the two numbers be 'x' and 'y' when u add them u get 110 that is x + y = 110 and when you subtract them you get x - y = 28.

now u can use substitution or just add the two equations x+y+x-y = 110 + 28 to get 2x = 138

x + y = 110

x - y = 28

2x = 138



simplified to x = 138/2 which is x = 69

Now u can just put this into either equation and solve for 'y' that is 69 - y = 28 so y = 41

so your answer is B (41)



question 3:: let the apples be 'a' and the oranges be 'o'.

two apples and six oranges cost 5.60 while

six apples and two oranges cost 4.80

2a + 6o = 5.60

6a + 2o = 4.80

this time you can subtract the 2 equations. remember the goal is to eliminate either one of the variables. (in this case to eliminate either 'a' or 'o' and solve for the other). Also in this case we are only asked to find 'o', the price of an orange, so it is faster to eliminate 'a' first and get our answer.

In order to do that first multiply equation 1 with 3. Now subtract the 2nd equation from the first to eliminate the variable 'a'



eq1 times 3 gives 6a + 18o = 16.80

subtract - 6a - 2o = - 4.80

and you get 16o = 12 and so o = 12/16 o = 0.75 that is one orange costs $0.75. answer is C ($0.75)



question 4:::for the last question u have to remember that the ordered pairs are represented as (x, y) that is the first number is a value for x while the second number is a value for y.

the easiest way to solve a question like this is to simply substitute the values of x and y from each ordered pair in to y>3 and y<2x+2 and check to see if the equations are satisfied.



check A. right from the start we can eliminate A as a potential answer because the value of y is give as 2. but from the question we know y>3. so A is not your answer no need to even check the 2nd equation.



checkB: y is given as 4 which works for eq1. for eq2 put x=2 and check if it holds...

y< 2(2) + 2 to get y <6 which holds since y=4. so B is a solution.



checkC:: same wya as B, C is also a solution



CheckD:: same way as A, D is not a solution

Answer 2

Answer 20] let the greater no. be x and smaller no. be y. x plus y = 110 and x minus y = 28 adding both. . 2x =138 =>x=69 =>x plus y=110 =>69 plus y=110 => y=110 minus 69 => y = 41 the smaller no. is 41. wxwwtvwx001 dd

Answer 3

Seems like you got your answer. for future reference I found a great site that has all the math formulas and theorems set to well known music. These really helped my daughter when she was struggling in math. I think this is the url...if not you should be able to google it.

http://www.math-songs.com

Answer 4

to respond to this, you would be able to desire to understand the three dynamics formulae linking speed, acceleration, time and distance. stick to those to the acceleration and relentless speed components to grant a formulation for the gap travelled. you recognize the entire distance so which you would be able to then clean up the subject.