Which solution for z makes the equation true?? 10+10+z=40=10 (pls explain why. Thanks)

Answer:
z=30
Step-by-step explanation:
40-10=30
10+10+?=30
30-10-10=10
I'm sorry cuz I don't know how to explain it
Answer:
z = 10
Step-by-step explanation:
10 + 10 + z = 40 - 10
10 + 10 + z = 30
10 + 10 + 10 = 30
since 40 - 10 = 30, then Z has to equal 10 because 10 + 10 + z needs to be 30