so here we have to find z , so we shall do it like
-3z - 5 = 10
( Now out here , we will take -5 to the other side , and when we take one variable or digit to other side , we change its sign, so we will also turn -5 to just 5 thats positive)
-3z = 10 + 5
(and now simply add)
-3z = 15
(now we will take -3 to the other side and divide it by 15)
z = 15/-3
(now simply divide)
z = -5 ANSWER
I hope you have understood by now but if not then pls be free to ask!
hope this helped!
+11912 
