Question

find the principal which after 8 months will amount to Rupees 8320 at 6% per annum simple interest

Answer 1

amount=principal +interest

interest=p*r*t/100
r=rate
t=time=8/12 for year
p=principal
interest=p*6*8/12*100
interest=p/25

amount=p+p/25
8320=26*p/25
320*25=p
8000=p

Answer 2

let the principal be x
here time =8 months = 8 /12=2/3 yrs
now SI = A-P
or PTR/100=A-P
Or x*2/3*6/100=8320-x
x*4/100+x= 8320
or 104x/100=8320
or x= 8000
so the principle is 8000 rs