Mr. Dufensmirtz is creating this year's final exam for his Precalculus students. Last
year's exam had 10 multiple choice questions and 7 open response questions. This
year he would like the ratio of multiple choice to open response questions to be 4:1.
How many more multiple choice questions does Mr. Dufensmirtz need to add to last
year's exam to achieve the desired ratio?

Options:
12
4
16
18
Please explain how and thank you!!!!