How do you solve 8x+15=3x-20?

3 Answers
May 9, 2018

x=-7

Explanation:

show below

8x+15=3x-20

8x-3x=-20-15

5x=-35

x=-7

May 9, 2018

The solution to the equation is x=-7

Explanation:

Start by getting like terms on the same side of the equation, I'll subtract fifteen from both sides first:

8x+15=3x-20
8x=3x-35

Next, subtract 3x from both sides:

5x=-35

And finally, divide by 5 on both sides.

(color(red)(cancel(5))x)/color(red)(cancel(5))=(-35)/5

The fives on the left cancel each other out (because (5x)/5=x), leaving us with this:

x=(-35)/5

x=color(red)(-7)

May 9, 2018

Re-arrange the equation, and you will find that x=-7

Explanation:

First, we'll add and subtract values from both sides such that all of the x-terms and their coefficients will end up on one side, and the constants will be on the other:

8x+15color(red)(-3x)=cancel(3x)-20color(red)(cancel(-3x))

8xcolor(red)(-3x)+15=-20

5x+15=-20

5xcancel(+15)color(red)(cancel(-15))=-20color(red)(-15)

5x=-20color(red)(-15)

5x=-35

Now that the equation has been rearranged as we like it, we'll divide both sides by x's coefficient. In this expression, the coefficient is 5:

(cancel(5)x)/color(red)(cancel(5))=(-35)/color(red)(5)

x=(-35)/color(red)(5)

color(green)(x=-7)