Question

A canoe travels 4 miles per hour downstream and 2 miles per hour upstream.

Let x represent the canoe's speed with no water current (still water) and y
represent the speed of the water current, in miles per hour. Then the situation
can be represented by this system of equations:
Choose the two correct options.
x + y = 4
x - y = 2
A. The speed of the water current is 1 mile per hour.
B. The speed of the canoe in still water is 3 miles per hour.
C. The speed of the canoe in still water is 1 mile per hour.
D. The speed of the water current is 3 miles per hour.

Answer 1

A, B

Explanation:

Given the system of equations, we should first solve for x and y so we can answer this question:

equation 1: x + y = 4, equation 2: x - y = 2 ⇒ add both equations together

x + y + x - y = 4 + 2 ⇒ combine like terms

2x + 0y = 6 ⇒ divide both sides by 2

x = 3 ⇒ plug into the x + y = 4 equation to solve for y

3 + y = 4 ⇒ subtract 3 from both sides

y = 4 - 3 = 1

Since we know y is the speed of the water current and x is the canoe's still water speed, we know that the water current's speed is 1 mph and the canoe's still water speed is 3 mph

This corresponds with choices A and B