She is buying 4 paint tubes. 4 x 8.5 = 34. 34 - 20 = 14, which is less than 54.
So since this is a linear equation, which is y=mx+b, you use what it tells you in the word problem. so mx is the rate, since in this equation 200 per ton of sugar that's your mx, so its 200x. then for your b value, which in this case is the cost of truck rental, so its 5,400.
your equation is C=200s+5400
the variables are the same so you can use Y and X, but I used the variables used in the word problem.
Y=200x+5400
The easiest way to solve this is by elimination.
3x - y = 6
6x + y = 21
Since you have a negative and positive y with the same coefficients (1), they cancel, and you add the other terms so it would look like:
9x = 27
Then solving for x leaves you with x = 3
Then you take the x value of three and plug it into to either of the equations, so
3(3) - y = 6
9 - y = 6
subtracting 9
-y = -3
then dividing by -1
y = 3
so the solution is x = 3 y = 3 or (3,3)
11 times 12 is 132
Becuas she is spending her money it would be negative
so c
Your answer would be 108 surface area