Answer :
Ok we can call one of the invested amounts x and the other 2500-x
From this we can say that x*0.08=interest and that (2500-x)*0.12=interest
As these two values are the same this can be written as:
x*0.08=(2500-x)*0.12
0.08x=300-0.12x
0.2x=300
x=1500
Therefore they invested $1500 at 8% per annum and $1000 at 12% per annum
From this we can say that x*0.08=interest and that (2500-x)*0.12=interest
As these two values are the same this can be written as:
x*0.08=(2500-x)*0.12
0.08x=300-0.12x
0.2x=300
x=1500
Therefore they invested $1500 at 8% per annum and $1000 at 12% per annum