Answer:
There are 5 multiple-choice questions.
Explanation:
You would want to set up two equations to solve this. So, you would write x+3y=50, where x is equal to the number of multiple-choice questions and y is equal to the number of short answer questions. The second equation would be x+y=20, where x and y stand for the same thing. We can set these up because we know that the amount of points has to equal 50 and that the number of questions has to equal 20. To continue to solve this, we can use substitution. To do this, first we need to solve for x in x+y=20. To do this, simply subtract y from each side to get x=20-y. Now, we can plug 20-y in for x in the equation x+3y=50. That would look like this: (20-y)+3y=50. Simplify the equation so you now have 20+2y=50, then subtract 20 from each side to get 2y=30, then divide by 2 on each side to get y=15. This means that there would be 15 short answer questions and 5 multiple choice questions. You can check this by doing 15x3=45 and 5x1=5, then add those together and you get 50 points total.