Joelle A. answered • 11/13/15
Tutor
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Math and Science tutor and teacher with international experience.
Brice,
We need to write and equation in slope intercept form. This form looks like y=mx+b where m is the slope and b is the y-intercept. In word problems, you can often think of this form as
(total) = (cost of each thing)×(number of things) + (cost even if there are no things)
Let's use this for your question.
Here we are told a that a rental is $2. What if I got 3 movies? it would be $6 rental... this $2 is the cost of each movie that you rent. it goes in the place of m. so our equation is
(total) = 2×(number of things) + (cost even if there are no things) or you could use y=2x+b
Next, do we know how many movies you are taking out? No, here in your question we don't know that so we use x for the unknown number of items. Now our equation is
(total) = 2x + (cost even if there are no things) or you could use y=2x+b
What if you went to the movie store and were ready to take out a movie, but were not able to pick one before you had to go. Was there anything you had to do before you could rent a movie? Yes, you had to buy a card before you could rent a movie. This is the amount you would have to pay even if you did not rent a movie. This value is b. So now our equations are
(total) = 2x+ 10 or you could use y=2x+10
Last question, do you know how much you paid in all? No, so this is our final variable y. The equation is y=2x+10.
Try solving another problem and use these four questions to help you write the equation.
For x ask "What item am I counting/buying/renting?"
For m ask "When I count/buy/rent one more, what changes? How much does it change?"
For b ask "What amount is there even if I count/buy/rent none?
For y ask "What what is the total amount after I have counted,bought,rented all I need?"
Then put your answer in order in the form y=mx+b
Let me know if you need any more help with this.
