Final answer:
To find the number of questions on the test, set up a proportion using the given information: 18/x = 90/100. Simplify the equation and solve for x to find that there were 20 questions on the test.
Step-by-step explanation:
To find the number of questions on the test, we can set up a proportion using the given information. Let x represent the total number of questions on the test.
Since Wendy answered 18 questions correctly and obtained 90%, we can set up the proportion:
18/x = 90/100
Cross multiplying, we get:
18 * 100 = 90 * x
Simplifying, we find:
1800 = 90x
Dividing both sides by 90, we get:
x = 20
Therefore, there were 20 questions on the test.