To factor out the coefficient of a variable you divide it by the sum.
10[(6 + 4) / 2]
10[10/2]
10 * 5
50 <==
For a parallelogram, the parallel sides must be the same length. This means you can set their lengths equal to each other. Get like terms on the same side to calculate x.
3x-5=2x+3
3x-5+5=2x+3+5
3x=2x+8
3x-2x=2x-2x+8
x=8
x=8
It is a function if it only touches the vertical line once.
