Answer:
x=-5
Step-by-step explanation:
ABN + NBC = ABC
ABN = x+85 NBC = x+105 ABC = 180
Substituting these in
x+85 + x+105 = 180
Combine like terms
2x +190=108
Subtract 190 from each side
2x+190-190=180-190
2x = -10
Divide by 2
2x/2 = -10/2
m∠ABC = m∠ABN + m∠NBC
We have m∠ABC = 180°, m∠ABN = x + 85 and m∠NBC = x + 105. substitute:
180 = (x + 85) + (x + 105)
180 = (x + x) + (85 + 105)
180 = 2x + 190 subtract 190 from both sides
-10 = 2x divide both sides by 2
-5 = x
