autumnthrasher1228
contestada

On Chatty Cathy’s cell phone plan she pays for minutes used plus a fixed monthly charge. For 500 minutes she pays $35 total, and for 1500 minutes used she pays $55 total.

What is her monthly fixed charge?

Respuesta :

TaeKwonDoIsDead

Answer:

$25

Step-by-step explanation:

500 mins = $35 (fixed + per minute charge)

1500 mins = $55 (fixed + per minute charge)

If we let per minute charge be "m"

and

let fixed charge be "f"

we can write 2 equations as:

35 = 500m + f

and

55 = 1500m + f

Now,

We re-write both equations in terms of f and equate both expressions:

f = 35 - 500m

and

f = 55 - 1500m

Equating:

35 - 500m = 55 - 1500m

-500m + 1500m = 55 - 35

1000m = 20

m = 20/1000

m = 0.02

Now we find f, what we are looking for:

f = 35 - 500m

f = 35 - 500(0.02)

f = 25

So, the fixed charge is $25