Question

Olivia is considering two phone plans. Plan A charges $20 per month, plus $0.05 per minute. Plan B charges $15 per month plus $0.10 per minute. How many minutes can Olivia talk so that both plans will cost the same amount? (Hint: Create an equation for each plan where y is the total cost and x is the minutes and then find the solution to the system of equations.)

Answer 1

Step-by-step explanation: Answer is 10

For this type of problem, we need to create a slope intercept equation for both.

Let's start by making one for plan a. We know that there is 20 dollars per month, this is the y intercept. Now, although it says per month which can change by x, the problem is mainly asking for minutes.

Remember, a slope intercept equation is

y=mx+b

M is the slope, and x is multiplied to the slope. The slope for an example can be used for this, adam eats 5 apples per day or x, how many apples can he eat in 5 days? We are wanting to know how many he can eat in 5 days, so we of course would multiply 5 by 5. This is basically a slope equation.

So, for plan a, we have y=0.05x+20 where x is minutes

For plan b, we should get

y=0.10x+15 where x is also minutes. The problem is asking use to find which value that we plug in will make both plan a and b correct. Basically, the value we find is x, so we solve for x by setting the two equations equal.

0.05x+20=.10x+15 Use inverse operations

20=.05x+15

5=.05x

x=10

We know if we plug in 10 for x, both would equal the same or 21 dollars.