-149 would be your answer
The Greatest Common Factor: G C F ( 45, 90 , 75 ) = 15
The greatest number of stones Marco can make is 15.
45 : 15 = 3
90 : 15 = 6
75 : 15 = 5
He will use: 3 red, 6 blue and 5 yellow tiles in each stone.
You get the nearest whole number by rounding if the number is 5 or more you round up 4 or less round down...in this case you're rounding the decimal and the first number after the decimal is 4 so you round to....
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