math
posted by Annie on .
Your teacher is giving you a test worth 100 points containing 40 questions. There are twopoint and fourpoint questions on the test. How many of each type of question are on the test?
How would you set this up?

Suppose there are x 2pointers and y 4pointers.
x + y = 40
2x + 4y = 100
If you are learning algebra, you probably know what to do next.
You could double both sides of the first equation and subtract what you get from the second equation, for example. That would give you 2y = 20 right away. 
Ok you have to write a system of equations.
x+y=40
2x+4y=100
y=40x
2x+4(40x)=100
solve: X=30 Y=10
then 30+y = 40
y=10 
I totally understand now! i had the 2x+4y=100...i just was blanking out about how to set up the 2nd part but I see now! Thank you so much! :)

what is the fraction lowes terms and a decimal 54

Xy=5
4x+6y=120