9a + 5b + 5c = 9
Multiplying the whole equation by -2.
-18a - 10b - 10c = -18.
Hence, the answer is -18.
Answer: 
Step-by-step explanation:
Given
New mail carrier takes 4 hours for delivery i.e.
New mail carrier completes 
part of work in 1 hour
Old mail carrier takes 3 hours for delivery i.e.
mail carrier completes 
part of work in 1 hour
If they work together, they complete the work in x hours i.e.
Answer:
h - d = 477 meters
Where: h = original height
d = amount the helicopter descended
The original height of the helicopter is given to be h
Step-by-step explanation:
Answer:
4 pound
Step-by-step explanation:
From the question :
2 gallons of water = 8 pound bag
Number of pound bag per gallon of water ;
Let the number of pound = x
Using cross multiplication, we'll have :
2 gallons = 8 pounds
1 gallon = x pounds
Cross multiply
2x = 8
x = 8 /2
x = 4
Hence, 1 gallon of water mixes 4 pound bag of concrete.
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