Question 70

If 80% of X is 36 more than 60% of Y and 120% of X is equal to Y, then the difference between X and Y is:

Solution

80% of x is 36 more than 60% of y

i.e;0.8x=36+0.6y-------------(1)

it is also given that 120% of x is equal to y

i.e; 1.2x=y-----------(2)

solving equation (1)

0.8x-0.6y=36

2(0.4x-0.3y)=36

0.4x-0.3y=18--------------(3)

given y=1.2x

substituting this in equation(3)

0.004x=18

x=18/0.04=450

substituting x value in y=1.2x

y=1.2$$\times\ $$450

=>y=540

now x-y=540-450=90

hence answer is 90 (optionC)

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