Question 906804
a+b=28
a=b+4
Take the known value of a from the second equation and put it into the first.
a+b=28
(b+4)+b=28
2b+4=28
Subtract 4 from each side
2b = 24
Divide each side by 2
b = 12
If b is 12, then a is 12+4, or 16