Homework: writing an equation from a verbal description

Tonight the eighth grade students should write an equation for the following situations:
1.Eight times a number equals 64.
2.A number divided by 9 equals 108.
3.The difference between the number of boys, b, and 13 girls is 4.
4. The amount of money Horace made this week, m, is twice the amount of money he made last week.