When 30% of one number is subtracted from another number, the second number reduces to its four-fifths. What is the ratio of the first to the second number?
A 3 : 2
B 2 : 3
C 2 : 5
D 4 : 7
Solution
Correct Answer: Option B
Let,
the first and second numbers be x and y,
ATQ,
y - 30% of x = y (4/5)
⇒ y - (30x/100) = 4y/5
⇒ y - (3x/10) = 4y/5
⇒ (10y - 3x)/10 = 4y/5
⇒ (10y - 3x)/2 = 4y
⇒ 10y - 3x = 8y
⇒ - 3x = 8y - 10y
⇒ 3x = 2y
⇒ x/y = 2/3
∴ x : y = 2 : 3