Let y be the temperature
Let m be the rate of temperature drop in degrees per hour
Let x be the number of hours elapsed since 8PM
The initial temperature (at x = 0) is 0
y = mx
Four hours from 8 PM, the temperature was -16.8 degrees
-16.8 = m(4)
m = -4.2 degrees per hour
At 9PM, one hour will have elapsed.
y = -4.2(1)
y = -4.2 degrees
YoYo. 15/6 = 2.5 so each YoYo costs $2.50.
1.

or if you mean (3x^3+5x^2+3x-7)+(8x-6x^2+6):

2.

Answer: 13
Step-by-step explanation:
I used Pythagorean theorem to solve this problem. As DC and AD is 12 and 5, you would do 12²+5²= c². 12²= 144 and 5²= 25. 144+25= 169. It doesn't end there. Do the square root of 169 ---> √169=13.
Area is 3.6*3.6*pi
Area is 12.96 pi