You can form an equation for the number, x. What is meant by "of a number"?
5x - 3y = -11 (×2)
2x - 6y = -14 (x5)
10x - 6y = -22
10x - 30y = -70
---------------------- -
24y = 48
y = 2
The answer would be 1 1/4, or 1.25.
The answer is -2.75
-0.5m + 2.75m - 5m
(-0.5m + 2.75m) -5m
2.25m - 5m = -2.75