Answer:
By using the rule that the interior angles of any triangle equal 180 we see that:
m<ABC+m<CAB+m<ACB=180°
Therefore,
(2x+15)+(x+10)+(3x+5) = 180°
Now we have an equation and can solve for x:
Combine like terms:
(2x+15)+(x+10)+(3x+5) = 180°
6x+30=180°
6x+30-30=180-30
6x=150
x=25
To check our work just plug in 25 for x in each equation and the sum of those answers should add up to 180:
2x+15
2(25)+15
65
x+10
25+10
35
3x+5
3(25)+5
75+5
80
65+35+80=180
x=25 is valid
Explanation: