Find the value of two numbers if their sum is 12 and their difference is 2

Can someone check if i did this right since i really want to make sure it’s correct. if you do you so much

1) you deposit $2,500 in an account that earns 4% simple interest. how much do you earn in eight years?

Money off coupons have been circulated to 300 households. only 2/5 of these were redeemed (used) in the local supermarket to get a free shampoo. what fraction of coupons were unused? (ps: write how you got the answer)