Question 1941
1. let x = number of questions on test, so (70/x)*100 = 80

Rearranging gives x=(70/80)*100, x=87.5 which is odd, so i guess the answer is 87 questions, since 70 out of 87 is 80.4%

2. number of correct answers = y, so (y/75)*100 = 80

y= 60

3. you try this

4. you try these. Remember a percentage is a fraction...30% means 30/100 etc

jon