If the cost of 8 erasers and 5 sharpeners is Rs.31/-, what will be the cost of 24 erasers and 10 sharpeners?  Choose the most appropriate option:  A) Rs.62/-  B) Rs.84/-  C) Rs.78/-  D) Rs.150  E) None of these
Explanation:   By analysis, we get 8x2 = 16 (erasers)   5x3 = 15 (sharpeners)   :.1 Eraser costs Rs.2/- and 1 sharpener costs Rs.3/-   Hence, the cost of 24 erasers + 10 sharpeners = 24x2 + 10x3 = 48+30 = Rs.78/-   Answer: Option Rs.78/-
<result>C</result>
If the cost of 8 erasers and 5 sharpeners is Rs.31/-, what will be the cost of 24 erasers and 10 sharpeners?