Question

Let the function f be defined by f (x) = 5x - 2a,

where a is a constant. If f (10) + f (5) = 55, what
is the value of a ?
(A) -5
(B) 0
(C) 5
(D) 10
(E) 20

Answer 1

Answer: 5

Explanation:

`f(10)=50-2a\\\\f(5)=25-2a\\ \\ f(10)+f(5)=75-4a=55 \implies a=5`