The exact vaule of cos(247.5 degrees)

We can set up equations to help us out

8x + 15= y

10x=y

If she has a 3 hour job, we can plug 3 in for x to find out which is better

8(3) + 15=y
24 + 15= y
39=y for a landscaping service

10(3)=y
30=y for a neighbors help

Since it will cost her 9 dollars less, she should go with the neighbor

D