A chess team is ordering customized T-shirts for a competition. The table shows the cost of ordering different numbers of T-shirts. Write a linear model that represents the cost as a function of the number of shirts.

Number of T-Shirts= 5, 10, 12, 18
Cost (In dollars)= 80, 140, 164, 236

COULD YOU PLEASE HELP ME I HAVE BEEN STRUGGLING WITH THIS PROBLEMS FOR A WHILE!!

Best answer that i found on yahoo ok   set :   x= length of 2nd piece in cm  x- 3= length of 1st piece in cm  x-4= length of 3rd piece in cm  then since you know they all came from the 20 cm ribbon you add them together and set them equal to 20x+ x-3 +x-4 = 20  3x - 7= 20  3x= 27  x= 9  the shortest piece is the third piece which is x- 4  x-4  9-4 = 5  the length of the smallest piece is 5 cm.  the other lengths are  9 cm  6 cm