Simplify the expression: 3x + 2y -7x + c + y

The important thing in this question is the letters. We want to group "like terms" together. This is what makes the expression simpler. 

I go about this by drawing a different shape around each letter. i.e the x terms would have a square, the y terms a circle and the c term a triangle.

The most important thing to remember when doing this is that the sign (that is, the plus/minus) BEFORE the term must stay with that term. This determines whether we add or subtract this from the other "like terms".

Once we have circled them, we can take each set of like terms and deal with them seperately. For example, the x terms would come to 3x - 7x. At this point, we deal with the numbers and don't worry about the letters, i.e we perform 3-7, this will come to -4, and, putting the letter back on, we get -4x. We do this with each set of like terms, and then put them back together.

This will give us the simplified answer -4x+3y+c.