Question

how do i simplify 3(3z-4)-(20z-5)

Answer 1

multiply first!
9z-12-20z+5 then solve!

Answer 2

Use the distributive property:
3(3z-4) - (20z-5)
= 9z-12 - (20z-5)

Since there is a "-' sign in front of the second half of the expression, the signs will change
9z-12 -20z+5

Simplify the rest:
-11z - 7