If m + n = 5 and 2m + 3n = 15, then m - n = _____?
- -8
- 20
- -5
- None of these
Explanation
Given equations:
m + n = 5 ... (1)
2m + 3n = 15 ... (2)
Multiplying equation (1) by 2:
2m + 2n = 10 ... (3)
Subtracting equation (3) from equation (2):
(2m + 3n) - (2m + 2n) = 15 - 10
n = 5
Substituting n = 5 in equation (1):
m + 5 = 5
m = 0
Now, m - n = 0 - 5 = -5
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