Question

The ratio of prices of onion, last year and this year $5:6$. The ratio of potato, last year and this year is $7:8$. The sum of prices of $1kg$ of onion and potato this year is $Rs.48$. Find the price of onion (in Rs.) last year if it was $\left(\frac{20}{21}\right)$ of the price of potato last year?

• A. $15$
• B. $20$
• C. $25$
• D. $24$

Answer 1

Answer: (B)

$20$

Let the price of onion last year be $5a$ and this year be $6a$

Let the price of potato last year be $7b$ and this year be $8b$

Given, $6a+8b=48$ -- (1)

Also, $5a=\frac{20}{21}\times 7b$

$=>a=\frac{4}{3}b$ or $b=\frac{3}{4}a$

Substituting $b$ in eqn 1 we get

$6a+8\times \left(\frac{3}{4}a\right)=48$

$=>6a+6a=48$

$=>12a=48$

$=>a=4$

So, cost of onion last year $=5a=$Rs $5\times 4=$Rs $20$