Somebody please help me witht the 2nd and 3rd

Apublic library wants to place 4 magazines and 9 books on each display shelf. the expressions 4s +9s represents the total number of items that will be displayed on s shelves. simplify this expression

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!

Given: ∆mop p∆mop =12+4 3 m∠p = 90°, m∠m = 60° find: mp, mo