The simple interest on a certain sum for 4 years at the rate of 15% p.a. is Rs.4500 less than the simple interest on the same sum for 6 years at the same rate of interest. Find the sum.
If p:q = 5:2, then p2 - q2 : p2 + q2 = ?
Simplify the following
15 ÷ 5 of 3 x 4 + 8 ÷ 12 of 4 x 12 - 4 ÷ 5 x 20