Jika a:b = 2:5 dan b-a = 7

a : b = 2 : 5
5a = 2b
a = (2b)/5
b - a = 7
b - (2b)/5 = 7
(5b -2b)/5 = 7
3b = 5.7
3b = 35
b = 35/3
b - a = 7
a = b -7
a = 35/3 -7
a = 11 2/3 -7
a = 11 14/21 - 7/21
a = 11 7/21