I think you could times 4 and 5 to get 20
Suppose :
2^x = t ..**&**.. 3^y = u
_____________________________
t + u = 9 × 3 3t + 3u = 27
=====》
2t - 3u = 8 2t - 3u = 8
+ __________
5t = 35
5 × t = 5 × 7
t = 7
&
u = 2
________________________________
Thus :
2^x = 7 ===》 x = Log _ 2 { 7 }
3^y = 2 ===》 y = Log _ 3 { 2 }
