First set up the equation:

Then substitute in known values:

and solve for C

Answer:
8.75%
Step-by-step explanation:
If she pays $135 eight times then she pays a total of 135 x 8 = $1080.
She had a down payment of $225, so that added on becomes $1305.
1305/1200 is 1.0875, which is an increase of 0.0875 over the original.
0.0875 x 100 = 8.75% increase.
Were doing the same test its a.
Distance = rate x time
D = 450 mph x 2.5 h
D = 1,125 miles