Question

ando ke dam 20% kam hojane se ek admi 90 me ab 15 ande aur jyada kharid skta h to uska ghanti dam aur purve dam bataiye

Answer 1

Let price of one egg = x
in 90, he can buy = 90/x eggs

if price is decreased by 20%
price of one egg = x - 0.2x = 0.8x
now he can buy = 90/0.8x

Since it is 15 more than earlier,

$\frac{90}{0.8x} - \frac{90}{x} =15\\ \\ \Rightarrow \frac{90}{x}(\frac{1}{0.8}-1) =15\\ \\ \Rightarrow \frac{90}{x}(\frac{1-0.8}{0.8}) =15\\ \\ \Rightarrow \frac{90}{x}(\frac{0.2}{0.8}) =15\\ \\ \Rightarrow \frac{90}{x} \times \frac{1}{4} =15\\ \\ \Rightarrow x= \frac{90}{15} \times \frac{1}{4}= \frac{90}{60}=Rs.\ 1.50$

Initial price(poorvi dam) = Rs. 1.50
Final price(ghati hui dam) = 0.8×1.50 = Rs. 1.20