Question

A student solved this problem by working backward.



Janice went shopping with her mom and at the end of the day she had $59.50 left over. She spent $13.65 on a T-shirt, $22.99 on some new sandals, and $40.75 on a new skirt.



How much money did Janice have at the beginning?



Student's solution - Janice had $59.50 left. Add up all the amounts she spent ($13.65 + $22.99 + $40.75) and add to the amount she has left over ($77.39 + $59.50). So Janice had $136.89 to begin with.



Solve this problem.



Dale was fixing his fence. At the end of the day, he had 12.5 feet of wood left over. During the day he had used one 3.5 foot long piece of wood, two 5.9 foot long pieces of wood, and one 10 foot long piece of wood.



How many feet of wood did Dale have at the beginning of the day?

Answer 1

We can also work backwards with this problem. Dale used 3.5+2(5.9)+10=25.3 feet of wood to fix his fence during the day, and was left over with 12.5ft. This means that he started off with 25.3+12.5= 37.8ft of wood at the beginning of the day.

Answer 2

it looks like you have already solved the first question,, so i will help you out with the second one then.
first, you will need to add together all of the used pieces of wood.
3.5 + 5.9 + 5.9 + 10 = 25.3 
now you need to add the 12.5 left over with the amount of used wood that we just found out.
25.3 + 12.5 = 37.8
this means that he had 37.5 feet of wood at the beginning of the day.
let me know if you have any further questions 
:)