mohon bantuannya ya kakak - kakak, terima kasih

a + b = 20
a = 2/3 b

a + b = 20
2/3 b + b = 20
(2/3 b + b) x 3 = 20 x 3
2b + 3b = 60
5b = 60
b = 12

a = 2/3 b
a = 2/3 x 12
a = 8

a x b = 8 x 12 = 96