Question

From the equations 7a = 4 and 7a + 4b = 12, one can conclude that b is?

Please explain the work behind the solution

Answer 1

7a=4
7a+4b=12
you substitute 4 in for 7a because it tells you in the first equation that 7a=4
4+4b=12
next you subtract 4 from each side
4b=8
next you divide 4 from each side
b=2
and theres your answer

Answer 2

if 7a=4
then 7a+4b=12 is equal to
4+4b=12
4-4+4b=12-4
4b=8
4b/4=8/4
b=2