a. This is just asking to find two variables that add up to 66, with boundary conditions. So, start by saying that 66 = x + y, and then impose the boundary conditions on x and y in a separate equation:
(2/5)*x = (5/8)*y + 10. In words, this equation says "Two fifths of x is ten more than 5/8ths of y", which is the same as your problem. From here, you just need to solve the second equation for x (or y), plug it into the first equation (66 = x + y), and then get the other variable.
b. This is very similar. All we need to do is find the two equations that control this system. Remember that a rectangle's perimeter is L + W + L + W = P, or 2L + 2W = P, where P is the perimeter, W is the width, and L is the length. The two equations you have here are that 2L + 2W = 36, and that L = 3W + 2. Here, just plug the L in the second equation into the first equation directly to find W, and use that W to find L.
I think the problem here is the wording, "Exceeds by ____". That threw me for a second too, but if you just think about it, you can see what it means. For example, if I were to say "X exceeds 5 by 3", you would know that X is 8. You can write this algebraically as "X = 5 + 3".