Using words or pictures, explain how you would use the sum 13 to show how to add in any number

Sally deposited money into a savings account paying 4% simple interest per year. the first year, she earn $75 in interest. how much interest will she earn during the following year?

You have 37 coins that are nickels, dimes, and pennies. the total value of the coins is $1.55. there are twice as many pennies as dimes. find the number of each type of coin in the bank.

Each weekday davina rides her bike from her house to school. after school, she rides to the library. then davina takes the same route to get home. these locations are shown on the grid below, where 1 unit on the grid represents 1 kilometer. how many kilometers does she ride each day? 10 16 20 32