What does pi equal to?

In a school 2/3 of the students study a language of those who study a language 2/5 study french

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!

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.