A cell phone company offers a contract which cost C, in dollars, of t minutes to telephoning is given by C=0.25(t-400)+57.95, where it is assumed that t is greater than and equal to 400 minutes. what times keep cost between $98.95 and $138.95?

For the cost to be between 98.95 and 138.95, the telephoning must be between ? minutes and ? minutes?

I don't even know where to start

To determine the range of minutes that keep the cost between $98.95 and $138.95, we can rearrange the given equation and solve for t.

Given equation: C = 0.25(t - 400) + 57.95

To simplify, let's first subtract 57.95 from both sides:
C - 57.95 = 0.25(t - 400)

Next, we divide both sides of the equation by 0.25:
(C - 57.95) / 0.25 = t - 400

Now, let's simplify the left side of the equation:
4(C - 57.95) = t - 400

Expanding the left side:
4C - 231.80 = t - 400

Rearranging the equation to isolate t:
t = 4C - 231.80 + 400

Combining like terms:
t = 4C + 168.20

Now, we need to find the range of minutes that keeps the cost between $98.95 and $138.95. We substitute these values into the equation and solve for t:

When C = $98.95:
t = 4(98.95) + 168.20
t = 395.80 + 168.20
t = 564

When C = $138.95:
t = 4(138.95) + 168.20
t = 555.80 + 168.20
t = 724

Therefore, the range of minutes that keep the cost between $98.95 and $138.95 is 564 minutes to 724 minutes.