A motorboat travels 9 miles downstream (with the current) in 30 minutes. The return trip upstream (against the wind) takes 90 minutes. Which system of equations can be used to find x, the speed of the boat in miles per hour, and y, the speed of the current in miles per hour? Recall the formula d = rt.

x=12 mile/hour(the speed of the boat)

y=6 mile/hour(the speed of the current)

Step-by-step explanation:

According to the Question,

let, x be the speed of the boat in miles per hour and y be the speed of the current in miles per hour.

x+y=18 Equation 1

x-y=6 Equation 2

On Adding both above Equations We get,

2x=24  ⇔ x=12 mile/hour(the speed of the boat)

& x+y=18 put Value of x=12 we get  ⇔ y=6 mile/hour(the speed of the current)

(0,-3) see attached graph

step-by-step explanation:

a. to solve the system, graph the two equations.

x = y+3 becomes y=x-3 has m=1/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move up 1 unit and 1 unit to the right. plot a point and connect.

y=-4x+3 has m =-4/1 and b=-3. start at (0,-3) on the y-axis and plot a point. then move down four units and to the right 1 unit. plot a point and connect.

the solution is the point (x,y) where the two lines intersect. by the graph below it is (0,-3).

b. to solve by substitution, substitute y = -4x-3 into x= y+3

x= (-4x-3) +3

x=-4x

5x=0

x=0

now substitute x = 0 back in to find y.

y= -4(0)-3

y=0-3

y=-3

solution is (0,-3)

c. use elimination by adding the equations together.

x-y=3

4x+y=-3

5x=0

x=0

then substitute into one equation to find y.

y=-4(0)-3

y=-3

answer: give more info

step-by-step explanation: