In 8 months, money earned by Bachhu Manjhi = Rs. 24000
In 1 month, money earned by him
= Rs. 24000/8 = Rs. 3000
(a) In 1 year, he earns = Rs. (12 × 3000) = Rs. 36000
(b) Number of months for earning Rs. 3000 = 1
Number of months for earning Rs. 4200
= 42000/3000
= 14