Question

Geeta bought eggs at Rs 8.40 a dozen.. At what price per hundred must she sell them so as to earn a profit of 15 percent?

Answer 1

we first take out the cost of eggs per 100

let x be the cost of eggs per 100. then,
8.40/12 = x/100  <direct proportion>
=  8.40×100 = 12x
=  840/12 = x
= 70 = x
the cost of eggs per 100 is Rs70.

15% of 70 = 15/100×70 = 10.5
70+10.5 = 80.5

Geeta must sell the eggs at the cost of Rs80.50 per hundred to earn a profit of 15 percent.

Answer 2

Cost of 1 egg =
8.40/12 =  Rs 0.7
Cost of 100 eggs =
0.7 * 100
= Rs 70
It costs Rs 70 for buying 100 eggs.
15/100 * 70
= 10.5
70 + 10. 5
= Rs 80.5
Geeta must sell the eggs at 80.5 Rs to gain a profit of 15%.