It’s a if you look at it close
An exterior angle of a triangle is 180 degrees is never true. The simple reason behind this logic is that 180 degrees means a straight line and it is not possible for a straight line to create an exterior angle of a triangle. I hope that this answer will come to your help.
Question 1143037: How many gallons each of 25% alcohol and 5% alcohol should be mixed to obtain 20 gal of 16% alcohol? That equals 3.2 gallons pure, checks.
m∠3 = 180 - m∠8 = 180 - 123 = 57
m∠1 = m∠3 = 57°
