A car is driving down a road at a normal speed of 50 mph. It enters a hilly area of gradual incline and decline, where it must drive 50 miles uphill and then 50 miles downhill. If this 100-mile section of road takes 2.6 hours to
traverse instead of the expected 2 hours (the time it would take if the road was completely flat), determine the
speed that the hills add or subtract when going over.
A. 24 mph
B. 32 mph
C. 37 mph
D. 12.5 mph

tube or goog would be a great resource to with that question

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.