Question

Y=30m+12t

y=15m+15t
how many minutes can you use your phone on both plans for the same cost?
what is the cost?

Answer 1

1/5 of a minute they are equal.

The cost would be $18

Explanation:

Something does not look right. You would not have 3 variables.

Set the two equations equal to each other and solve for m. I think that the variables t may be an error.

30m + 12 = 15m + 15 Subtract 15 m from both sides

30m -15 m + 12 = 15m -15m + 15

15m + 12 = 15 Subtract 12 from both sides

15m + 12 - 12 = 15 - 12

15m = 3 Divide both sides by 15

`(15m)/(15)` =
`(3)/(15)`

m =
`(1)/(5)`

Cost:

y = 30m + 12

y = 30(1/5) + 12

y = 18

y = 15m + 15

y = 15(1/5) + 15

y = 3 + 15

y = 18