Question 87

If 3y + 2x = 47 and 11x = 7y then what is value of y - x ?

Solution

This is a system of two equations with two unknowns.

3y + 2x = 47 and
11x = 7y

Multiplying the first equation by 7, we get 21y + 14x = 329
And, multiplying the second equation by 3, we get 33x = 21y

So, 21y + 14x = 329 or 33x + 14x = 329
Hence, 47x = 329

So, x = 7 and y = 11

Therefore, y-x = 4 and the correct answer is option (a)

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