Question

What is the value of f(7)

Answer 1

F(7) means f(x) when x = 7. The x is replaced with 7.

So we'll replace every x with 7 to go from x = 7 to 3-x = 3-7 = -4

Put another way
f(x) = 3-x
f(7) = 3-7
f(7) = -4

Answer: -4

Answer 2

Answer. -4.
 *f - 3 = -5 (x-0) 
f= -5x + 3 

*f - (-3)= -5 (x - 1) 
f + 3 = -5x +4 
f= -5x+5 -3 
f= -5x+1