how do you solve a system of equations

Question

an exam will have 20 questions and be worth a total of 100 points. there will be a true/false section where the questions are worth 3 points each and a short essay section where the questions will be worth 11 points each. how many essay questions will there be on the test

Answer 1

x+y= 20   1)

3x+11y=100  2)

3x+3y=60 3) multiply 1) by 2

8y=40 4) subtract 3) from 2)

y=5 (divide by 4)

x+5=20

x=20-4=15

 

15 T/F 5 essay