book Maths Puzzle Numerical Ability

Could you help me solve this problem?

Find and simplify where possible.

f(x)= x squared -5 if x is 2f (-3)

Read Solution (Total 0)

book Other Question

7 10
-- = ----
d+5 d=2
I am very confused as to how to Solve each system by the additional method. Can someone help me understand this and solve it please?

17.) x + y = 48
12x + 14y = 628