
Martin S. answered 04/09/20
Patient, Relaxed PhD Molecular Biologist for Science and Math Tutoring
Let's call the T/F questions variable t, and the multiple choice questions variable m. There are 30 total questions, so t + m = 30, The total points on the test is 100, and since the T/F questions are worth 4 points each, the total you can get from those is 4t. Similarly, the total points you can get from multiple choice is 3m. Put these together and 4t + 3m = 100.
Now, solve one variable in terms of the other using the first equation
t + m = 30, subtract t from both sides and m = 30 - t.
Substitute 30 - t for the m term of the second equation
4t + 3(30-t) = 100, distribute the 3.
4t + 90 - 3t = 100, simplify by combining the t terms
t + 90 = 100, solve for t
t = 10
Now plug 10 in for t in the first equation, t + m = 30, so 10 + m = 30, and so m = 20
so there are 10 T/F questions and 20 multiple choice questions
Hope this helps