Question

Last summer,emelian decided to measure change in a swimming pools water level each week. It was hot and dry the first week and the level decreased by 8 inches.During the second week, it rained and the water level increased by 17 inches. Model the changes as a sum of integers.

Answer 1

(-8) + (+17) = -8 + 17 = 9

Explanation:

Level of water in the first week = - 8 (the negative sign represents a decrease in inches, of the level of water)

Level of water during the second week = + 17 (the positive sign represents an increase, in inches, of the level of water).

These changes in the level of water can be modelled as sum of a positive and a negative integer as follows:

(-8) + (+17)

When adding a negative and a positive integer value, subtract the smaller value from the greater value, and retain the sign of the value that is greater.

17 is greater than 8. Therefore, subtract 8 from 17, and retain the sign of 17.

Thus:

(-8) + (+17) = -8 + 17

= 9