Question

amir lent Rs. 600 to hameed for 2 years and Rs. 150 to aman for 4 year and received altogether from both Rs. 90 as simple interest. the rate of interest is.

Answer 1

Interest = Pin = principal * interest rate * number of years

Let interest rate be i, then
600*i*2+150*i*4=90
1200i+600i = 90
i=90/(1200+600)=90/1800=1/20=0.05 or 5%