Answer:
75%
Step-by-step explanation:
One way to find this out is to divide 15 by 20
15/20 can be simplified into 0.75.
Another example:
Let's say a student does absolutely horrendus on the test, and gets only 4 questions correct out of 20. You can do 4/20 which is 0.2 in decimal form. (You can use a calculator.) This means that in this example, this student got a 20% on the test.