Easey peasy
oposite angle is equal
other angles are supplementary (supplementary means add to 180, and a straight line=180 so if you look at 2 lines intersecting and think for a little bit, you wiill see why)
oposite angle=30
other angle is adds to 180
30+other=180
subtract 30
other=150
other is oposite other other
other=other other
150=other other
angles are
150,30,150
60% of 20 quizzes = 60/100*20 quizzes = 12 quizzes
Amount of quizzes remaining = 50 quizzes - 20 quizzes = 30 quizzes
He passes 80% of those 30 quizzes, so
80/100 * 30 quizzes = 24 quizzes
So, he passed 12 quizzes from the initial bunch and 24 quizzes from the rest, which totals to 12 quizzes + 24 quizzes = 36 quizzes.
Then, you see that he passed 36 quizzes, out of the total 50 quizzes, so the ratio is 36 quizzes / 50 quizzes = 36/50, which when converted as a percentage is 36/50 * 100% = 72%.
Therefore, he passed 72% of the quizzes for the entire year.
