What is the missing step in this proof?

To determine the number of deer in a forest a forest ranger tags 280 and releases them back

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!

What 8/12+8/11 in another way than and improper fraction