I'm not sure how your school teaches it, but here is how I learned factoring.
1.Make a box with a line through the middle.
2. Put 7 in one side and +28w in the other.
3. Prime factor the terms and put them under the numbers. Prime factor of 7 is 7 and 1 (you don't have to put the 1 under the 7). Prime factors of 28 is 7*2*2.
4.Find common factors. In this case:7. Circle the 7 in each side of the box and write a 7 to the left of the box. Now put what is remaining on top. Since there is nothing in the 7 box anymore put a 1 on top. 2*2 and the plus sign is still in the other side so put +4 on the top.
Now you have your answer. The number to the left is the number outside the parentheses. The numbers on top are in the parentheses. 7(1+4)
