tolong doing 3a Dan 3c

pakai permisalan
3^x = a, 4^y = b

a - b = 5
3a + b = 23
----------------- +
4a = 28
a = 7

a =7 subsitusi ke a-b = 5 shg 7-b = 5 jadi b = 2

3^x = 7 maka x = 3'log7
4^y = 2 maka y = 1/2