Increases & Decreases
An anchor on a boat lowers at 2.75 feet per second. What is the change in depth after 8 seconds?
8 (-2.75) =
-22 feet
Solve:
12−(−9)
21
The _______ of a number always represents the distance that a number is from zero on a number line.
absolute value
The number -4 is the _______ of 4.
Opposite
The temperature at 4:00 p.m. was −6 °C, and then it fell by 7°C.
Write an expression to represent the new temperature?
-6 - 7 = -13
Over 5 hours the water in the pond increased by 18.5 gallons. It rose at a constant rate.
Write an equation to represent the change in the number of gallons of water in the pond each hour.
18.5 gal / 5 hours = 3.7 gallons/hour
Solve:
12(-3)
-36
3 − 8 2/3
-5 2/3
Which of the following statements is true?
B. The absolute value of a number is never negative.
The temperature at 7:00 a.m. was 12°C, and at 7:00 p.m. it was −10°C.
Write the equation to represent the difference in the temperatures.
12 - (-10) = 22
Johnny bought pizza 4 times. Each time it cost $23.45. He also got $45 for his birthday and deposited it in his account. What is the total change in his bank account?
4(-23.45) + 45 =
(-93.80) + 45 =
-48.80
Decrease of $48.80
-4 + (-3) - 2
-4 + (-3) - 2
-4 + (-3) + (- 2)
-7 + (-2)
-9
−2.7−1.8
-4.5
The value of which expression is positive?
D. 5−(−4)−3
5+4+(-3)
9+(-3)
6
Samantha owes $25.50, and borrows another $20.00. She pays back $15.25 of her debt and then earns $45.00. Later, Samantha pays back $22.50 of her debt.
How much debt does she still have to pay back?
7.75
The pool temperature dropped 12 degrees in 3 days. Write an expression and determine what is the change in temperature each day ?
-12 / 3 =
-4 degrees per day
Solve:
−3 / (−3)
9
(Positive 9)
5 1/5−(−2 4/15)
7 7/15
The value of which expression is negative?
D. 2+5−17
2+5+ (-17)
7 + (-17)
-10
Mr. Jakarta is having a well built in his backyard. On Monday, 175 feet of the well was dug, and another 165 feet was dug on Tuesday. How many feet deep was the well dug relative to ground level?
-340
A butterfly is flying 8 3/4 ft above the ground. It descends to a spot 6 1/4 ft, what was the elevation where the butterfly lands?
8 3/4 - 6 1/4 =
2 2/4 or 2 1/2 ft.
Solve:
−8+2
-6
46.33−(−15.07)
61.4
What is the rule for subtracting a negative?
Subtracting a negative is the same as adding a positive.
Tyesha needs 17 3/4 feet of wood for a project. She has lengths of wood that a 7 1/2 feet, 5.25 feet, and 6 3/4 feet long. Does she have enough wood for her project? How much extra does she have or how much more does she need?
Yes she has 1 3/4 extra