PLEASE HELP ME with linear equation?

the table below gives you the cost of ordering different boxes. in each case it includes shipping charge

# of boxes: 2 4 6 8 10
total cost: 27 39 51 63 75

write an equation that gives you the cost as a function of the number of boxes shipped? what is the shipping charge????
please help me my equations is not coming out right different answer every time =( i would REALLY APPRECIATED if u help me =)

If you plot the points: (2,27), (4,39), (6,51), (8,63), (10,75),
you'll see that they describe a straight line.

Fit the line (substitute varous points into: y = mx + b); and you'll get:

... y = 6x + 15

or Total Costs = 6 * Number of Boxes + 15 ← your fixed costs
....................... ↑ ..... your costs to ship / box

let x is the number of boxes, and y is the cost.
from the table you have many points, you need two of them only as follows
slope=y2 - y1/x2 - x1
y-27/x-2 = 39-27/4-2
y-27/x-2 = 12/2 = 6
by cross multiplication
6x-12 = y-27
y = 6x - 12 + 27
y = 6x + 15
so the equation will be :
y= 6x + 15
or: 6x - y + 15 = 0
to know the shipping charge put the number of boxes = 0, i.e. x = 0, so now the total cost will include the shipping charge only.
y = 6(0) + 15 = 15
therefore the shipping charge = 15

chat = 6*b + 15, with R^2 = 1.

The shipping charge is 6.

15 is the fee.