You need to get 70 % * 200 = 70/100 * 200 = 140 problems right, so you are allowed to get the remaining 60 wrong.
You can get 60 questions wrong and get a 70 percent but if you get 61 wrong you are at a 69.5 percent.
20 wrong.
24 problems
Each question is worth 2.5 percent. You can get 8 wrong.
15 wrong
You can get 18 wrong.
not many problems, only that you would get the problem wrong:)
24 wrong answers
You can get 20 questions wrong.
You can get 63 questions wrong and get 70%.
30
14 of them.