Cindy is saving for a trip to Hawaii. Each week, she puts aside the same amount of money for her airfare. After 9 weeks of saving, she needs $390 more for her airfare. After 14 weeks, Cindy still needs $240. How much does Cindy put aside each week for her airfare? How much is the airfare to Hawaii?

I might be wrong but I did the calculations and my answer is that she put $30 aside each week and the airfare to hawaii is $660

Step-by-step explanation:

This is how I find my answer

first:

14 weeks - 9 weeks = 5 weeks

$390 - $240 = $150

$150/5 = $30 ( that is what she save per week)

then I did

$30 x 140 = 420 + 240 = $660

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.