<PRE><B>Question 187302</B>
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 .
</PRE>