Question 568280
The costs C and income I for making and selling T-shirts with a school logo are given by the equations C=$535+4.50n and I=$12n, where n is the number of T-shirts. 
a. How many T-shirts must be bought and sold to break even? Explain. I got that the answer to this one is $72 as you cannot make 71.3 shirts.
C=$535+4.50n and I=$12n
535+4.5n = 12n
535 = 6.5n
n = 72 when rounded up
====================================
 
b. Suppose only 50 shirts are sold. Is there a profit or loss. I said Loss.
OK
----------------------- 
C. Suppose the income is $1,200. Is there a profit or loss. I said profit.
So n would be 100 : So profit.
---------------------------- 
WHERE I NEED HELP
d. i. For each equation, find the coordinates of a point that lies on the graph of the equation.
{{{graph(400,400,-20,125,-200,1000,12x,535+4.5x)}}}
ii. What information does this point give?
That is the equilibrium point (72,864).
That is where I = C
------------------------
iii. Describe how to use the equation to see that the point will be on the graph.
Replace n and C with the numbers
Replace n = I with the numbers
Since (72,864) satisfies both equations that
point is the solution for the system of 
two equations.

====================
Cheers,
Stan H.
==============
====================================