Answer: 493,700,000
Step-by-step explanation:
Your answer would be D) -3°F/hour
Look at it this way...
47°F at 7:20pm
46°F at 7:40pm
45°F at 8:00pm
44°F at 8:20pm
43°F at 8:40pm
The temperature is going down by 1°F every 20 minutes so...
-1°F/20 minutes
Obviously there's no answer choice that says that so you'd need to change the minutes into an hour...
So an hour is 60 minutes and 60/20 = 3
So if you do 3・-1
You get the answer... -3°F/hour
Alrighty
remember

means

and

and

for all real values of x
so

means

means

which simplifies to
1=x²+4x-5
minus 1 both sides
0=x²+4x-6
use quadratic formula or complete the square

and

2 solutions
18bags
Look if 1=3 2=9 3= 18 so he uses 18 bags!
Yessss that should be correct