Hey there!
-15z + 7(8 + 4z)
DISTRIBUTE 7 WITHIN the PARENTHESES
= -15z + 7(8) + 7(4z)
= -15z + 56 + 28z
COMBINE the LIKE TERMS
= (-15z + 28z) + (56)
(WE LEFT 56 ALONE BECAUSE IT DOES NOT HAVE ANY LIKE TERMS!)
= 56 + 13z
= 13z + 56
Therefore, your answer is: 13z + 56
Good luck on your assignment and enjoy your day!
~Amphitrite1040:)