Given the equations below, what is the value of mn?
2(m+n)+ m = 9; 3m – 3n = 24

A 5

B -3

C 12

D -15

Solution

Correct Answer: Option D

Given, 3(m-n) = 24
⇒ m = 8+n
Now, 3m+2n = 9
⇒ 3(8 + n) + 2n = 9
⇒ 5n = -15
⇒ n = -3
Again, m = 8+n = 8 - 3 = 5
So, mn = 5 × (-3) = -15

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