The expression 15 n + 5 n + 5 Which is another way to write this expression?

Cora bought a package of erasers. there are 4 pink erasers and 12 blue erasers. what is the ratio of pink erasers to blue erasers?

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

Jonathan can type 20 documents in 40 minutes ,and susan can type it in 30 minutes and jack can type it in 24 minutes working together ,how much time will it is take them type the same document