M varies directly w/ the difference of squares of A & B. M=10, A=5, and B=3

Question

I need to find the constant or k of variation for my homework, please help. Need to submit ASAP!! It's from our lesson direct squared variation but I left my notes on class :(

Answer 1

M = k(A² - B²)

Since M = 10 when A = 5 and B = 3, 10 = k(25 - 9)

So, 16k = 10

k = 5/8