SAT Math?
posted by Lacey on .
I'm working on a couple of SAT math programs for school, and I have trouble figuring some out.
1. Joe is 3 years younger than Kate. If n represents Nora's age now, what was Kevin's age 4 years ago, in terms of n?
A. N + 7
B. N + 1
C. N  1
D. N  4
E. N  7
2. If (x + y)^2  (x  y)^2 = 84 and x and y are positive integers, which of the following could be a value of x + y?
A. 10
B. 12
C. 14
D. 16
E. 18
Thanks so much in advance!

1. Not possible to solve. Too many kids named.
2. You have a diference of two squares, it factors to (x+yx+y)(x+y+xy) which reduces to 2y*2x=4xy or then solve for x,y
4xy=84
xy=21 and 7 and 3 fit that real nicely.