Answer:
$43.75
Explanation:
Let the 2 situations given represent 2 points on the line. The number of km he drives is the x coordinate, and the amount he earns is the y coordinate:
These 2 points will be (7, 17.4) and (12, 25.9)
Using these points, find the slope using rise over run (y2 - y1) / (x2 - x1)
Plug in the points:
(y2 - y1) / (x2 - x1)
(25.9 - 17.4) / (12 - 7)
8.5 / 5
= 1.7
Next, plug in the slope and a point into y = mx + b to find the y intercept:
y = mx + b
17.4 = 1.7(7) + b
17.4 = 11.9 + b
5.5 = b
Plug the slope and the y intercept into y = mx + b to get the equation:
y = 1.7x + 5.5
Using this, find his earnings if he drives 22.5 km. Plug in 22.5 as x:
y = 1.7x + 5.5
y = 1.7(22.5) + 5.5
y = 43.75
So, if he drives 22.5 km, he will earn $43.75