Jane has a pre-paid cell phone with Splint. She can't remember the exact costs, but her plan has a monthly fee and a charge for each minute of calling time. In June she used 100 minutes and the cost was $54.00. In July she used 660 minutes and the cost was $138.00.

Express the monthly cost C as a function of x, the number of minutes of calling time she used.

And using the minutes from June we can find the value for b the intercept

And the function would be:

Step-by-step explanation:

For this case we define the following notation first:

C represent the cost for a given month

x represent the number of minutes of calling time she used

And we want to find a function of C in terms of x

We have the following info:

June

x =100 , C = 54

July

x =660 , C = 138

For this case we can assume that we can use a linear function since we have just two points given, and the general formula would be:

Where a is the slope and can be estimated as:

And using the minutes from June we can find the value for b the intercept

And the function would be:

answer: 21$

step-by-step explanation:

$42 / $14 = 3   (ratio 3: 1)

$7 x 3 = $21

pentagon

step-by-step explanation:

the coordinates   a(5, -2), b(3,-1),c(-4,-4) d(-3,8) and e(-1,4) forms the vertices of the polygon when they are connected in order.

in order to classify that which polygon is it with the given coordinates, first count the number of vertices and then count the number of sides it can make with these vertices.

since, the given coordinates have five vertices, therefore, it will make five sides. moreover, pentagon is regular in nature therefore it will be convex.

now, a polygon with five sides is known as pentagon, therefore, the given polygon is the pentagon.