document.write( "Question 793898: help ive got no idea where to start\r
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\n" ); document.write( "\n" ); document.write( "There are 100 monsters. 38 of them are visible, the rest are invisible. Amongst the visible
\n" ); document.write( "monsters, 16 glow red, 18 glow blue, 18 glow green, 7 glow red and blue, 5 glow blue and
\n" ); document.write( "green and 6 glow red and green. (Note that \16 glow red\" should be interpreted as: 16
\n" ); document.write( "monsters glow red, but each of those monsters is free to glow other colours too. The other
\n" ); document.write( "numbers should also be interpreted in the same way).
\n" ); document.write( "One day the monsters that simultaneously glow with all three colours, decide to join forces
\n" ); document.write( "with the invisible monsters, to form a mighty army. How many monsters are in the army?
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Algebra.Com's Answer #480591 by KMST(5328)\"\" \"About 
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The number of visible monster is said to be \"38\".
\n" ); document.write( "The rest of the 100 monsters is \"100-38=62\"invisible monsters.
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\n" ); document.write( "There are \"x\" monsters that simultaneously glow with all three colors, and they are counted in all the other numbers given.
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\n" ); document.write( "There are also \"D\" monsters that glow with exactly 2 colors.
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\n" ); document.write( "If you add
\n" ); document.write( "the 16 monsters that glow red, plus
\n" ); document.write( "the 18 monsters that glow blue, plus
\n" ); document.write( "the 18 monsters that glow green
\n" ); document.write( "you get \"16%2B18%2B18=52\".
\n" ); document.write( "That count of 52 glowing monsters exceeds the number of visible monsters.
\n" ); document.write( "If we were counting each visible monster just once we should add up to 38.
\n" ); document.write( "That means that some monsters are being counted more than once in that total of \"52\" because they glow with two or three colors at once.
\n" ); document.write( "The difference, \"52-38=14\" includes \"D\" (each dual color monster counted once), plus \"2x\" (2 extra counts for each triple color monster), so
\n" ); document.write( "\"14=D%2B2x\"
\n" ); document.write( "Adding the numbers of monsters that glow with at least two colors at once we get
\n" ); document.write( "\"7%2B5%2B16=18\". That includes \"D\" (each dual color monster counted once), plus \"3x\" because each triple color monster is counted 3 times, once for each pair of colors.
\n" ); document.write( "So \"18=D%2B3x\"
\n" ); document.write( "\"system%2814=D%2B2x%2C18=D%2B3x%29\" --> \"x=18-14=4\"
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\n" ); document.write( "That might army includes the 4 triple color monsters, plus the 62 invisible ones, for a total of \"62%2B4=highlight%2866%29\"
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