Question

solve each problem.
21
the temperature at noon on a summer day was 88°c. at midnight, the temperature had dropped 12°. what was the temperature at midnight?
22
a submarine is in the middle of the ocean at a depth of 115 feet. it dives to a depth of 4 times its initial depth. what is the new depth of the submarine?
23
a scuba diver is at a depth of 82 feet. he descends another 19 feet. what is his new depth?
24
a group of hikers is descending a mountain at a rate of 400 feet per hour. after 3 hours, what integer represents their total change in elevation?
25
a roller coaster begins at 90 feet above ground level. then it descends 105 feet. find the height of the coaster after the first descent.

Explanation:

Step1: Calculate midnight temperature

$88 - 12 = 76$

Step2: Calculate submarine's new depth

$115 \times 4 = 460$

Step3: Calculate diver's new depth

$82 + 19 = 101$

Step4: Calculate elevation change

$-400 \times 3 = -1200$

Step5: Calculate coaster's new height

$90 - 105 = -15$

Answer:

1. $76^\circ\text{C}$
2. 460 feet
3. 101 feet
4. $-1200$ feet
5. $-15$ feet (15 feet below ground level)