Answer:
For 180 miles of driving the two plans will cost the same, at a price of $84.
Explanation:
1 - Set up the system of equations
Let x represent the miles driven
Let y represent the cost
First Plan:
y = $48 + $0.20x
Second plan:
y = $57 + $0.15x
Note that both are set equal to y, that means we can substitute y in one equation with the other equation because y = y
2 - Substitute
$57 + $0.15x = y = $48 + $0.20x
$57 + $0.15x = $48 + $0.20x
3 - Get the variables on one side and the constants on the other and then get x alone
$57 + $0.15x = $48 + $0.20x
- $48 - $48
$9 + $0.15x = $0.20x
- $0.15x - $0.15x
$9 = $0.05x
$9/0.05 = $0.05x/0.05
x = 180 Miles
"For what amount of driving do the two plans cost the same?
For 180 miles of driving the two plans will cost the same.
4 - Plug 180 in for x in either equation and solve to find the cost at which they equal
y = $48 + $0.20x
y = $48 + $0.20(180)
y = $48 + $36
y = $84
"What is the cost when the two plans cost the same?"
$84 is the cost when the two plans cost the same
Hope this helps