1st box:
m<A + m<B + m<C = 180
2nd box:
substitution property
3rd box:
division property of equality
Hope it helps.

Y is the total price. X is the number of months. 30 is a flat, one time payment.
Answer:
(3,1);(6,-2)
Step-by-step explanation:
I pretty much just looked at where they both intersected with each other and you'll get your answer.