6th grade math help me please

An advertising firm has an old computer that can prepare a whole mailing in 6 hours. with the of newer model the job is complete in 2 hours. how long would it take the newer model to do the job alone?

Which expression is equivalent to 8(k + m) − 15(2k + 5m)?

What fraction is equivalent to 0.46464646··· a. 46⁄99 b. 46⁄999 c. 46⁄100 d. 23⁄50