f(x)=4/5x-2
f(3)=4/5(3)-2
(4/5)(3/1)-2
12/5-2/1
Need to find the common denominator for -2/1 which is 5
-2/1 ( Multiply)
-2(5)-1(5)
12/5-10/5
f(3) =2/5
Answer: 2/5
