Question:
If 12 boys earn Rs 840 in 7 days, what will 15 boys earn in 6 days?
Solution:
Earnings of 12 boys in 7 days $=$ Rs. 840
$\therefore$ Earnings of 12 boys in 1 day $=$ Rs. $\frac{840}{7}=$ Rs. 120
$\therefore$ Earnings of 1 boy in 1 day $=$ Rs. $\frac{120}{12}=$ Rs. 10
$\therefore$ Earnings of 1 boy in 6 days $=$ Rs. $(10 \times 6)=$ Rs. 60
$\therefore$ Earnings of 15 boys in 6 days $=$ Rs. $(60 \times 15)$
$=$ Rs. 900