A motorboat travels miles in hours going upstream. It travels miles going downstream in the same amount of time. What is the rate of the boat in still water and what is the rate of the current

x = 49 mi/hr

y = 6 mi/hr

Step-by-step explanation:

A motorboat travels 258mi in 6 hours going upstream. It travels 330mi going downstream in same amount of time. What's the rate of the boat in still water and what is the rate of the current.

Let

x = the speed of the boat in still water.

y = the speed of the stream

The speed upstream is x - y

The speed downstream is x + y

Distance = rate × time

258 = (x - y)6 (1)

330 = (x + y)6 (2)

From (1)

x - y = 43 (3)

From (2)

x + y = 55 (4)

x - y = 43 (3)

x + y = 55 (4)

Add the equations to eliminate y

x + x = 43 + 55

2x = 98

x = 98/2

x = 49 mi/hr

Substitute x = 49 into (4)

x + y = 55 (4)

49 + y = 55

y = 55 - 49

y = 6 mi/hr

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.

a c

step-by-step explanation: