jika 6^x-2y = 1/216 an 4^x-y = 256, aka x+y = ...

jawab

6^(x - 2y)  = 1/216 = 6^(-3)
x - 2y = - 3

4^(x-y) = 256 = 4^4
x - y = 4

x - 2y = -3
x - y = 4  || (-)
-y = - 7
y = 7

x - y = 4
x = y + 4
x = 7+4
x = 11

x + y  = 11 + 7
x + y  = 18