Jawabanmu

2014-09-12T11:05:50+07:00
(a+b) (a-b) = 40
a+b = 40 / (a-b)
a+b = 40 / 4
a+b = 10
a-b = 4
----------  +
2a= 14
a=7

a+b =10
7 + b =10
b = 10 - 7
b = 3