21≥<span>3(a-7) +9
first, just solve it like a normal equation
Distribute
21</span>≥3a-21+9
<span>Combine numbers
21</span>≥3a-12
<span>Solve like equation
33</span>≥3a
11≥a
<span>"a" has to be less than or equal to 11 for the inequality to be true
</span>
Let the average speed at day time be x miles per hour
Therefore at night the average speed = (x + 10) miles per hour
Time = Distance / speed
Time at day - Time at night = 36 minutes.
36 minutes = 36/60 hour = 6/10 hour
Time at day = Distance / speed at day = 120 / x
Time at night = Distance / speed at night = 120 / (x + 10)
120/x - 120/(x + 10) = 6/10
1/x - 1/(x + 10) = 6/10* 1/120
1/x - 1/(x + 10) = 1/200
((x + 10) - x) / ((x)(x+10)) = 1/200
(x + 10 - x) / ((x)*(x+10)) = 1/200
10 / ((x)*(x + 10)) = 1/200
1 / ((x)*(x + 10)) = 1/2000
Therefore x (x + 10) = 2000
x and x +10 are 40 and 50. Because 40*50 = 2000
x = 40
Average speed in the day time = 40 miles per hour
Answer:
y = -x - 3
Step-by-step explanation:
y = mx + c
m = -1
y = -x + c
When x = 1, y = -4
-4 = -1(1) + c
c = -4+1 = -3
y = -x - 3
The answer is 26. I added an image that has the explanation for the problem.
