Jayden and Carson are selling T-shirts and sweatshirts for a fundraiser. Jayden sells 9 T-shirts and 3 sweatshirts for $420. Carson sells 1 T-shirt and 6 sweatshirts for $296. They use a system of equations representing the price of a T-shirt, t, and the price of a sweatshirt, s. Jayden and Carson graph the system of equations using t as the horizontal axis and s as the vertical axis. What is the point of intersection of the graph, and what does it represent?

Alternative Text

answer: c, the green line

step-by-step explanation:

there is no black line, eliminate b.

simple interest implies periodic payments, but the red line shows no payments, eliminate d.

simple interest has equal payments. if paid say every day, the graph is about a straight line (actually a stairstep).

the yellow line is not straight, eliminate a.

check: the green line is straight, answer is c.

simple interest with positive interest rate gives a straight line sloping up to the right. green line:

g(t) = $100 + ($200-$100) ÷ (20 years) × (t years)

= $100 + (4%/year) × ($100)(t years)

incidentally, the yellow line curving upward represents continuously compounded interest

y = $100 × 2^(t years / (14 assuming the yellow line hits $200 at 14 years. 2^0 is 1, so y(0) = $100; 2^(14/14) is 2, so y(14) = $200.