If we decrease half of a number by some value, we'd have to add that value and multiply the new number by 2 to take into account the 'Half of a number' part. So in this problem, what I would use is: (1/2)x - 19.7 = -4.1 Adding 19.7: (1/2)x = 15.6 Multiply by 2: x = 31.2
