Kiki wants to rent a bounce house for her daughter's party. The cost, y, to rent a bounce house for a number of hours, x, is shown in the table. The initial set-up fee is included in the cost.

You have to make 2 equations

185 = 2(x) + y
X is the hours and y is the setup fee

315 = 4(x) + y

Now you solve the first
185 = 2x+y
185-y = 2x
(185-y)/2 = x
That means you can plug that value into the second equation where you see the x

315 = 4((185-y)/2) + y
315 = 370-2y + y
315 = 370 - y
-55 = - y
55 = y
So y is 55 (the setup fee)

Back to the original

185 = 2(x) + y
185 = 2(x) + 55
130 = 2x
65 = x

Now test it

575 = 8x + y
575 = 8(65) + 55
575 =  520 + 55
575 = 575