choose your equation (btw they are written a tiny but differently but either way they are both the same answer)
A.) Well the first step is this: 50/50 is 1 right? right. so 1 + 40 = 41 - 60 = -19
B.) Well the first step is this: 50/50 is 1 right? right. so here 40-60=-20 + 1 = -19
