Answer:
x=5
Step-by-step explanation:
Angles in a triangle adds up to 180 degrees
so 105 + (6x+20) + (7x-10) = 180
simplify
115+13x=180
subtract 115 to each side
13x=65
divide by 13
x=5
check work
105 + (6(5) + 20) + (7(5) -10)
105 + (30 +20) +(35 - 10)
105 + 50 + 25 = 180
