z ÷ 3 - 4z + 4(z - 5); z = 15
z ÷ 3 - 4z + 4(z - 5) =
= 15 ÷ 3 - 4(15) + 4(15 - 5)
= 5 - 60 + 4(10)
= -55 + 40
= -15
Answer: -15
Substitution: 15 / 3 - 4(15) + 4(15-5)
The solving for some: 5 - 60 + 40
And the combining them: 45 - 60
And the answer is: -15
