Explanation:

Let P be the principle and R% per annum be the rate. Then, 
P(1 + R/100)3 = 10648 ....(i)
and P(1 + R/100)2 = 9680 .....(ii)
on dividing (i) by (ii), we have 
⇒ (1 + R/100) = 10648/9680 
⇒ R/100 =968/9680 = 1/10 
∴ R =100/10 = 10%