SOLUTION: Please help me solve this linear equation problem !!! A teacher gives out a test 0f 30 problems. Each computation problem is worth 3 points.Each word problem is worth 5 points.

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Question 187302: Please help me solve this linear equation problem !!!
A teacher gives out a test 0f 30 problems. Each computation problem is worth 3 points.Each word problem is worth 5 points. The total of points you can receive on the test is 110 points. How many computation problem are there?
Answer by dukesmart(20) About Me  (Show Source):
You can put this solution on YOUR website!
Put x= number of tests of computation problems
Put y= number of tests of word problems
we create the 2 equations as follows:

x + y = 30..........(1)
3x + 5y = 110.......(2)
multiply (1) to 3 then (1) will become 3x + 3y = 90 .....(3)
take (2) subtract (3) we have:
3x-3x+5y-3y=110-90
2y = 20
y =10
then x=30-10
x=20
answers: we have 20 computation problems .