Okay so here's what you do,
Add them,
[tex]2x + x + 15 + 2x - 20 = 180[/tex]
Collect the like terms,
2x + x +2x = 5x
[tex]5x + 15 - 20 = 180[/tex]
Calculate the sum / difference,
15 - 20 = - 5
[tex]5x - 5 = 180[/tex]
Move constant to the right side and change its sign,
[tex]5x = 180 + 5[/tex]
Calculate by adding,
[tex]5x = 185[/tex]
Divide both sides of the equation by 5,
[tex]5x \div 5 = x[/tex]
[tex]185 \div 5 = 37[/tex]
[tex]x = 37[/tex]
We're not done yet, x=37, now let's find out the measurements of each side.
To do this, simply substitute all expressions with x being 37,
[tex]2x = 2(37) = 74[/tex]
[tex]x + 15 = 37 + 15 = 52[/tex]
[tex]2x - 20 = \: 2(37) - 20 = 54[/tex]
Remember, a triangle always has 180° and do the measurements add up to 180??
[tex]52 + 54 + 74 = 180[/tex]
Yes, they do meaning it's correct & reasonable!
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I hope that helps you out!!
Any more questions, please just ask me!!
~ Zoey
