Let S = his average speed.
Let D = distance traveled one way
Time = distance / speed
Set up an equation:
d/6 + d/12 = 2d/S
Multiply the equation by 12s:
12s(d/6) + 12s(d/12) = 12s(2d/s)
Simplify to get:
2sd + sd = 24d
Combine like terms:
3sd = 24d
Divide both sides by d:
3s = 24
Divide both sides by 3:
s = 24/3
s = 8
His average speed was 8 mph.
By synthetic division,
-5 | 1 -6 -42 79
. | -5 55 -65
- - - - - - - - - - - - - - - - -
. | 1 -11 13 14


When

, you're left with a remainder of 14.
Answer: 0
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0
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0
1
2
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0
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0
2
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5
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5
0
0
Step-by-step explanation: