Answer:
30
Step-by-step explanation:
1. distribute the 5 on both pair of parenthesis...you will get 5z+20+10-5z
2. group the variables so when we group it we will get 5z-5z and 20+10
3. the 5z-5z cancels out so what we have left is 20+10 therefore it gives up the answer 30
