Simplifying
4x + -3y = 12
Solving
4x + -3y = 12
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '3y' to each side of the equation.
4x + -3y + 3y = 12 + 3y
Combine like terms: -3y + 3y = 0
4x + 0 = 12 + 3y
4x = 12 + 3y
Divide each side by '4'.
x = 3 + 0.75y
Simplifying
x = 3 + 0.75y
Answer:
18
Step-by-step explanation:
Since he does 90 cars-----5 days
x cars--------1 day
we multiply 90 by 1 then over 5
Multiply 240 by 5 to get 1200 miles then add the 40 from the first day so it took 5 days
To find the slope, use the equation of a line: 
Plug in the values for x and y:

We know that 2 can fit into 5 twice, which means 2*2 is 4.
We now have
.
If 5 is b more than 4, then this means that 4 is b less than 5. Subtract 4 from both sides, and you will have b = 1.
This means your equation is y = 2x + 1.
STEP 1:
Divide the length of the ribbon by the size of the pieces.
12 inches= 1 foot
= 9 ft ÷ 15 inch pieces
convert ft to inches
= (12)(9) ÷ 15
= 108 ÷ 15
= 7.2 pieces from one roll
STEP 2:
multiply the number of pieces that can be cut from one roll by the number of rolls
= 7.2 pieces * 5 rolls
= 36 pieces total from 5 rolls
ANSWER: The greatest number of 15-inch pieces that can be cut from five 9-foot rolls is 36.
Hope this helps! :)