You can solve this one by adding their rates, but you have to invert the numbers they give you to find the rate. Rate is measured in something per unit of time, and "per" indicates division. So the rates are: 1/3 of an hour (Sally) and 1/6 of an hour (Steve). So add the rates: 1/3 + 1/6 = 1/2. (1/3 is 2/6, and 2/6 + 1/6 = 3/6). Since their combined rate is 1/2 of a room in one hour, it takes them two hours to paint the room.
This answer makes sense: It takes Sally three hours by herself; with Steve's help, she's faster, but not THAT much faster, because he's pretty slow. You can often spot-check word problem answers like this by giving it a common sense once-over. If we came up with four hours, that would clearly be wrong: it should take her LONGER if she's getting help.
What's the question she got the answer wrong to?
2 negatives can be converted to a plus sign. -(-x) can be +x or just x.
-54--23
-54+23
<u>23-54=-31</u>
78--4
<u>78+4=82</u>
-48/-6
Now let's pause fer a sec. When a negative is being divided by another negative, the quotient(answer to division problem) becomes a positive.
<u>-48/-6=8</u>
<u></u>
<u>50*-4=-200</u>
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hope it helps
Answer:9x hope it helps
Step-by-step explanation:
Imagine A'V' is part of the dilated figure, and AV is part of the original figure.
A'V' = 3.2
AV = 3.2 + 4.8 = 8
A'V'/AV = 3.2/8 = 2/5
Answer: First choice, 2/5.
