Question 333505
Andrew invested a total of  18,000,
part at 5% . Let this investment  be x
interest = 0.05x
..
part at 9%.  this will be 18000-x
interest will be (18000-x )*0.09
..
interest from the 9% investment was Php100 less than his income from the 5% 
..
income from 5% - income from 9% = 100
..
0.05x - 0.09(18000-x)= 100
0.05x-1620+0.09x=100
0.14x=1620+100
0.14x=1720
x= 1720/0.14
= Php 12,286
..
investment at 9% will be 18000-12286
= Php 5,714
CHECK(0.05*12286) - 0.09(18000-12286)=100