5 and 1/2 - 2 and 2/5

First you will make the individual numbers into fractions, so for 5 and 1/2, multiply 5 times 2, and add the one that’s already there, and you will get 11/2, then for the other number, multiply 2 times 5 and add it to the two that’s there, and you will get 12/5. So now you have 11/2 - 12/5. You have to make the denominators the least common multiple, so if you look you can see they both go into 10. So multiply 11/2 times 5/5 and 2/2 for 12/5 (to get both of the denominators to 10). You should now have 55/10 - 24/10. Subtract only the nominators, leaving the denominators at 10, and you will get 31/10. You can’t simplify it any more, so that is the answer.

31/10 or 3.1

17 is c. congruent means equal in size