<span>Simplifying
3x + -1y = 12
Solving
3x + -1y = 12
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add 'y' to each side of the equation.
3x + -1y + y = 12 + y
Combine like terms: -1y + y = 0
3x + 0 = 12 + y
3x = 12 + y
Divide each side by '3'.
x = 4 + 0.3333333333y
Simplifying
x = 4 + 0.3333333333y</span>
Markup means they sell it for that percentage more than they bought it for. First let's calculate how much they will mark it up for:

Convert 87% into a decimal(87/100):

Multiply:

This is how much they'll mark it up, now let's add it to how much they bought it for to find out the selling price:
True
______
A closed circuit basically means everything is connected by wires and for this setup every device receives electricity making this true
Answer:
12
Step-by-step explanation:
x=2 was multiplied by 4 to get to x=8 so you multiply y=3 by 4 to make it y=12