Answer:
(b) 67
Step-by-step explanation:
A solution to the differential equation describing the temperature according to Newton's Law of Cooling could be written as ...
T = (final temp) + (initial difference)×(decay factor)^t
where the decay factor is the fraction of change during 1 unit of time period t.
__
Here, the initial difference of 100-25 = 75 degrees decays to 90-25 = 65 degrees in 1 minute. So, the units of t are minutes, the decay factor is 65/75, the initial difference is 75 degrees, and the final temperature is 25 degrees. That lets us write the equation as ...
T = 25 +75(65/75)^t
Then for t=4, the temperature is ...
T = 25 +75(13/15)^4 ≈ 67.3 . . . . degrees
After 4 minutes the temperature of the coffee is about 67 degrees.
Answer:
-6
Step-by-step explanation:
-2 ^3x3 = 24
-30 + 24 = -6
The expression is: 5x + 6y - 3
Answer:
(-31,15)
Step-by-step explanation:
Rotating 90 degrees clockwise is very simple:
(a,b) 90 degrees= (-b,a)
Very simple.
Just switch sides and add negative to the first term.
Answer:

Step-by-step explanation:
Let b be the number of balloons and h be number of party hats.
We have been given that balloons cost $0.50 each, so cost of b balloons will be 0.50b.
We are also told that party hats each cost $1.25, so cost of h party hats will be 1.25h.
Further, Joe wants to spend exactly $20 on the party supplies. We can represent this information in an equation as:

Therefore, the equation
represents the number of balloons ( b) and the number of party hats ( h) that Joe can buy spending exactly $20.