What sentence represents the number of test questions in the problem below?
A test is worth 50 points. Multiple-choice questions are worth 1 point, and short-answer questions are worth 3 points. If the test has 20 questions, how many multiple-choice questions are there?
A. The number of multiple-choice questions plus the number of
short-answer questions is 50.
B. The number of multiple-choice questions times the number of
short-answer questions is 20.
C. The number of multiple-choice questions minus the number of
short-answer questions is 50.
D. The number of multiple-choice questions plus the number of
short-answer questions is 20.