Answer:
Solution given:
time [t]=3years
principal [p]=Rs2400
rate[r]=?
simple interest [S.I]=Rs 576
we have
S.I=ptr/100
576=2400*3*r/100
576=72r
r=576/72
r=8%
now
principal [p]=Rs 4200
time[t]=2years
rate[r]=8%
simple interest [S.I]=?
we have
S.I= ptr/100=4200*2*8/100=Rs 672
The required interest is Rs 672.