Answer:
In order to subtract fractions, there must be a common denominator (the number on the bottom of the fraction). 7 and 3 can be multiplied to get 21 (a common factor). To get each fraction to have a denominator of 21, they can be multiplied by 3 and 7 respectively and then subtracted. Attached is an image of the problem worked out. I apologize for the messy handwriting. Hope this helps!
Step-by-step explanation: