A line is 180 degrees. Right? Okay. Although there is a line between them, both angles will sum up to 180 degrees. So the equation will be: 3x-20+x=180 You need to isolate the variable. First add like terms: 3x+x=4x So then the equation is 4x-20=180 After that you add 20 to both sides because the opposite of -20 is +20, and Denver what you do on one side needs to be reappeared to the other side 4x-20=180 +20 +20 4x= 200 Dived both by 4 4x=200 /4. /4 X=50
