[tex] \frac{a}{b} = \frac{2}{3} [/tex]
2b = 3a / · 2
4b = 6a
[tex] \frac{a + 12}{b+12} = \frac{4}{5} [/tex]
5(a + 12) = 4(b + 12)
5a + 60 = 4b + 48
5a + 60 = 6a + 48
5a - 6a = 48 - 60
-a = -12 / · -1
a = 12
[tex] \frac{a}{b} = \frac{2}{3} [/tex]
[tex] \frac{12}{b} = \frac{2}{3} [/tex]
2b = 3 · 12
2b = 36
b = 36 : 2
b = 18
a = 12
b = 18
