Question 983944
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X=cement; Y=sand=2X; Z=gravel=5X
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X+Y+Z=1000 cu. yds Substitute for Y and Z.
X+2X+5X=1000 cu yds
8X=1000 cu yds
X=125 cu yds ANSWER 1: There is 125 cu yds of cement.
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Y=2X=2(125 cu yds)=250 cu yds ANSWER 2: There is 250 cu yds of sand.
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Z=5X=5(125 cu yds)=625 cu yds ANSWER 3: There is 625 cu yds of gravel.
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CHECK:
X+Y+Z=1000 cu yds
125 cu yds+250 cu yds+625 cu yds=1000 cu yds
1000 cu yds=1000 cu yds