Hello! Percents are parts of 100. Jake got 85% of his answers correct, which means he got 15% of his answers wrong. To find out how many answers Jake got incorrect, all you have to do is multiply the amount of questions (20) by the percentage in decimal form. 15% is 0.15 in decimal form. 20 * 0.15 is 3. There. Jake got 3 answers incorrect on his math test.