Question 293431: I missed one class due to illness and now I am very lost. I think I need help determining which formulas to use for this word problem. I have plotted a few different ways and not sure if it makes sense. Here is the question:
Irvin's parents allow him to use the family car provided he pay for the gas, which averages $1.60 per gallon. The car averages 20 miles per gallon. To help Irvin earn gas money, this parents pay him $10 a week to do chores. Determine and then plot a weekly savings equation for Irvin that represents earnings minus money spent on gas. Write a physical interpretation for both intercepts of the savings equation.
I have tried having x=miles and y=allowance. I got a slope of 12.5 (which was cents per gallon of gas) I would appreciate any help on this.
Thank you so much.
Answer by richwmiller(17219)   (Show Source):
You can put this solution on YOUR website! Where is the equation?
What are you talking about with 12.5 cents per gallon? We are told it is $1.60 a gallon not $.125 per gallon.
What did you do with x=miles and y = allowance?
We are told " Determine and then plot a weekly savings equation for Irvin that represents earnings minus money spent on gas. Write a physical interpretation for both intercepts of the savings equation."
Each week he is given $10 but he spends 1.6 per gallon
x=gallons
y= savings
earnings =$10
minus gas expense
y=10-(1.60*x)
The problem told you how to set it up.
"plot a weekly savings equation for Irvin that represents earnings minus money spent on gas."
The y intercept is the earnings. If he doesn't buy any gas (x) he can save $10
So if x=0 then y=10
If he has no savings (y=0) then the cost of gas used up all his allowance
So if y=0 then 1.60*x=10 which is the x intercept of x=10/1.60=10/1.6=100/16
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