Answer is 8
Work Shown:
f(x) = sqrt(5*x + 4)
f(12) = sqrt(5*12 + 4) ... replace every x with 12
f(12) = sqrt(60 + 4)
f(12) = sqrt( 64 )
f(12) = 8
(2x + 3y)4
Distribute
4*2x = 8x
4*3y = 12y
8x + 12y
Answer: 8x + 12y
The answer is 72
b/c 80% is equal to .80
so you do 90x.80