If 10 men or 20 boys can make 260 mats in 20 days, then how many mats will be made by 8 men and 4 boys in 20 days?
(a)240
(b)260
(c)280
(d)520
Answer
Answer (as printed): B
Explanation
Let the required number of mats be $x$. 10 men $\equiv$ 20 boys $\Rightarrow$ 1 man $\equiv$ 2 boys $\Rightarrow$ 8 men $\equiv$ 16 boys $\Rightarrow$ (8 men + 4 boys) $\equiv (16+4)$ boys $= 20$ boys. $\therefore$ 8 men and 4 boys can make as many mats as 20 boys, i.e., 260 mats.
Explanation as extracted from the printed page; notation may be imperfect.