There is a total of 27 quarters stacked in four piles. The first pile has 5 fewer than the second pile. The second pile has 4 more than the third pile. The fourth pile has three times as many as the second pile. How many quarters are in the fourth pile?
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Solution:Note that:
- 27 quarters = 4 piles = 1st pile + 2nd pile + 3rd pile + 4th pile
- 1st pile = 2nd pile – 5 = 3rd pile – 1
- 2nd pile = 1st pile + 5 = 3rd pile + 4
- 3rd pile = 1st pile – 1 = 2nd pile – 4
- 4th pile = 3(2nd pile)
This means that…- 27 quarters = (2nd pile – 5) + (2nd pile) + (2nd pile – 4) + 3(2nd pile)
First, let’s find the number of quarters in 2nd pile.Open the brackets.- 27 quarters = (2nd pile – 5) + (2nd pile) + (2nd pile – 4) + 3(2nd pile)
- => 27 quarters = 2nd pile – 5 + 2nd pile + 2nd pile – 4 + 3(2nd pile)
Combine like terms.- => 27 quarters = (-5 – 4) + 6(2nd pile)
Simplify the RHS.- 27 quarters = -9 + 6(2nd pile)
Add 9 both sides.- 27 + 9 = 6(2nd pile)
- => 36 quarters = 6(2nd pile)
Divide 6 both sides.- => 6 quarters = 2nd pile
Now, substitute the number of quarters in 2nd pile in it’s equation.- 4th pile = 3(2nd pile)
- => 4th pile = 3(6)
- => 4th pile = 18 quarters.
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Answer: 18 quartersStep-by-step explanation:second pile = xfirst pile = x – 5third pile = x – 4fourth pile = 3xtotal amount of quaters = 27x + x – 5 + x – 4 + 3x = 276x = 36 x = 6fourth pile = 3(6) = 18