Answer and Explanation:
The line seems to pass trough the points (0,6) and (-3,4).
Slope is: 

The slope of the line should be
.
The X coordinate has to be 0
The cash price of the car includes the amount of the loan plus the amount of the down payment
Cash price=the loan of the car+down payment
First find the amount of the loan by using the formula of the present value of an annuity ordinary which is
Pv=pmt [(1-(1+r/k)^(-kn))÷(r/k)]
Pv the amount of the loan ?
PMT payment per month 355
R interest rate 0.071
K compounded monthly 12
N time 5years
Pv=355×((1−(1+0.071÷12)^(−12
×5))÷(0.071÷12))
=17,885.56
Cash price=17,885.56+2,500
=20,385.56....answer