Can some one tell me which method you used to solve the system

Chip worked at the animal shelter for 6 hours each week for several weeks. he worked for a total of 42 hours. which of the following can be used to find the number of weeks chip worked at the animal shelter?

Which is equivalent to 10/12? options: 10/18 5/6 3/12 9/11

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!