Question

5 - a - 11 = 4a - 21

Answer 1

5 - 11 + 21 = 4a + a

-6 + 21 = 5a 

15 = 5a

a = 15/5

a = 3                 ok

Answer 2

5-a-11=4a-21
-a-4a=-21+11-5
-5a=-26+11
-5a=-15 (-1)
5a=15
a=15/5
a=3 

A= 3