Answer:
-10 or 12
Step-by-step explanation:
1/2 y2 -y =60
Multiply both sides by 2
y2 - 2y =120
Subtract 120 from both sides
y2 - 2y -120 = 0
Factor the left side ( y+10) (y -12 =0)
By zero product property, y= -10,12
So the number is -10 or 12
I don't if this was helpful sorry if its not
