What is the constant in 15-8y

Could somebody me with this radical simplification?

Using elimination, what is -4x+2y=-12 4x+8y=-24

The evening newspaper is delivered at a random time between 5: 30 and 6: 30 pm. dinner is at a random time between 6: 00 and 7: 00 pm. each spinner is spun 30 times and the newspaper arrived 19 times before dinner. determine the experimental probability of the newspaper arriving before dinner.