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Question 202088: There are exactly four times as many submarines as there are aircraft. Which of the following can be the total number of submarines and aircraft combined?
1. 35
2. 63
3. 39
4. 41
I took algebra so long ago now, but there are a couple of questions like this and I just cán´t remember how to set the problem up.
Found 3 solutions by stanbon, Alan3354, Earlsdon:
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! There are exactly four times as many submarines as there are aircraft. Which of the following can be the total number of submarines and aircraft combined?
1. 35
2. 63
3. 39
4. 41
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Let the number of aircraft be "x".
Then the number of subs is "4x".
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Equation: x + 4x = 5x
So the total number of subs and aircraft must be a multiple of 5.
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Answer: 35
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Cheers,
Stan H.
Answer by Alan3354(69443)  (Show Source):
You can put this solution on YOUR website! There are exactly four times as many submarines as there are aircraft. Which of the following can be the total number of submarines and aircraft combined?
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If a = #of aircraft, then
4a is the # of subs.
a + 4a = 5a
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You can't have a fraction of a sub or an aircraft, so it's a whole number that's a multiple of 5.
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Only answer #1, 35 is a multiple of 5.
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It wasn't asked for, but there are 7 aircraft and 28 subs.
Answer by Earlsdon(6294) (Show Source):
You can put this solution on YOUR website! Try this:
For each aircraft (A) there are four submarines (4S) for a total of five weapons (5W).
Which of the four choices of answers is evenly divisible by five?
Just one of them, that's 35 or answer 1.
If you have to show this algebraically, then let W = number of weapons.
From the problem description, you have W = 1A and 4W = 4S, so...
W + 4W = 5W
Which answer is a multiple of 5?
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