Question

Nicholas’s sand castle is 81 cm tall but the wind is blowing away sand at a rate of 3 cm per minute. Nina’s sand castle is 36 cm tall and she is adding more sand to it at a rate of 6 cm per minute. After how many minutes, x, will Nina and Nicholas’s sand castles be the same height?

Answer 1

5 minutes

Step-by-step explanation:

Simple way to do this is by making a graph, you can start with 81 in one column and 36 in the other column. You can then start adding rows and subtracting 3 from 81 and adding 6 to 36 each row. By doing this pattern they end up matching at row 5 and they each are 66 cm tall.