Question

For what integers a and b do we have a=2b+21 and a=b-28?

Answer 1

a= -77

b=-49

Lets solve this step by step:

a=2b+21

a=b-28

substitute

b-28=2b+21

-21 on both sides

b-49=2b

b= -49

substitute b

a= -98+21

a= -77