80% of p = 220 (We know this as the sale price is 20% off, so there is still 80%)
0.8p = 220
p = 220/0.8 (This is because we are making p the subject of the formula)
p = 275 (If you are not allowed to use a calculator for this, then: 220/0.8 is the same as 2200/8 because we are just simply multiplying both the numerator and denominator by 10. This can be simply worked out by long division)
Jerry did the best at Spanish so the answer is D If you divide the numerators by the denominators of each class you get his percentage Math - 45/50 = .9 = 90% Science- 19/25= .76 = 76% Music- 8/10 = .8 = 80% Spanish 19/20 = .95 = 95%