The metro train costs $6.30 round trip to ride to work each day. you work 4 days a week (16 days a month). if you can get a monthly pass for $78, how much money can you save by buying the pass?

$22.80

Step-by-step explanation:

Given:

1 day trip costs = $6.30

Monthly working days = 16

Monthly pass = $78

Let's calculate the metro train costs for 16 days.

We need to multiply $6.30 by the number of days.

= 6.30 * 16

= $100.80

You suppose to pay $100.80 if you are not taking the pass.

If you take the monthly pass, you just need to pay $78.

The amount saved if you took the monthly pass = $100.80 - $78 = $22.80

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.