How to write 16 eighth as a power with base of 4

Julius sold five times as many computers as sam sold last year. in total, they sold 78 computers. how many computers did julius sell?

Some boys and girls were asked if they had a pet. one third of the group were boys. there were 20 boys. 20% of the girls had a pet. boys with a pet : girls with a pet = 1 : 5 i need to know how many girls there are.

Which shows the graph of the solution set of 3y – 2x > –18?