Chapter 1.5, Problem 12E

To determine

To Find: The final temperature of an item after initially freezing it to a negative temperature and then increasing its temperature by an amount.

Answer to Problem 12E

The final temperature is ${90}^{o}C$ .

Explanation of Solution

Given Information: The initial temperature is $-{18}^{o}C$ . The temperature is then increased by ${108}^{o}C$ .

Method:

• The final temperature is obtained by finding the sum of the initial temperature and the amount of increase in temperature.
• To find the sum of two numbers with opposite signs, subtract the smaller number from the larger number and put the sign of the larger number before the answer.

To find the sum of $-18$ and $+108$ , subtract the smaller number $18$ from the larger number $108$ to get $108-18=90$ . Since the larger number $108$ has a $+$ sign before it, put a $+$ sign before the answer.

Therefore, the final temperature of the item is $+90^{o}C$ .