Hello! I can help you! First things first, because they are both the same angles on opposite sides, let's set this up in the form of an equation and solve for "x". It would be set up like this:
2x + 20 = 3x - 30
You see up top that it says 2(x + 10). What you would do is multiply what's in the parenthesis by 2, in order to get 2x + 20. Then put the equal sign and write 3x - 30. Subtract 3x from both sides to get -1x + 20 = -30. Subtract 20 from both sides to get -1x = -50. Divide each side by -1 to isolate the "x". In this case, because you are dividing a negative number by a negative number, your quotient will be positive. -50/-1 is 50. Let's plug in the value as "x" and see if it works. 50 * 2 is 100. 100 + 20 is 120. 50 * 3 is 150. 150 - 30 is 120. 120 = 120. There. x = 50.
60% of 20 is (0.6 x 20) = 12 passes
There are a further 30 quizzes remaining (50 total during the year minus 20 already written)
80% of 30 is (0.8 x 30) = 24 passes
The student has passed (12 + 24) = 36 quizzes out of 50 total, giving an overall pass percentage of ((36 / 50) x 100)) = 72%.
