Question

Sam wants to compare surf board rental companies while he is on spring break. Catch-a-Wave has a flat rate of $60 for all day. Long Board has no initial charge, but it is $15 per hour. Beach Rentals only charges $5 per hour, but has an initial charge of $30.

Explain to Sam how he can graph these surf board rental charges and describe what key features of the graphs he should consider when making a decision.

Answer 1

any explanation is helpful im kind of stuck

Answer 2

Here's what you would want to remember doing this: y = mx + b
where m is the slope of the line and b is where the line crosses the y-axis.

Using this, we could deduce the equations for the lines described in your question.
For the first one, we would have a slope of zero and an intercept of 60 (because it is a flat rate). So y = 60.

For the next one we have a slope of 15 but no intercept (because there was no initial charge). So y = 15x.

For the last line, we have a slope of 5 with an intercept of 30 (because there was an initial charge). So y = 5x + 30.

Follow this link for a graph:
http://www.wolframalpha.com/input/?i=graph+of+y%3D60%2Cy%3D15x%2Cy%3D5x%2B30

What Sam would need to consider is where the lines intersect on the graph. He could look and see that the lines y = 60 and y = 5x + 30 intersect when x = 6. Here both lines have a value of 60. This means that Sam could use either the Catch-a-Wave or Beach Rentals for 6 hours and pay $60. If he used Long Board he would have to pay $90 for 6 hours of use (not a good deal).

If Sam wanted to use the surf board for longer than 6 hours he should use the Catch-a-Wave because it has just the flat rate of $60 a day.

Answer 3

thank you so much

Answer 4

No problem.