Let x represent the "smallest number" of a set of three unknown numbers.
• The greatest os 4 times the smallest, symbolically: 4x
• The middle number is three more than the smalles, symbolically x+3
• The sum of the smallest and the greatest is the same as 2 times the middle number, symbolically: x+4x=2(x+3)
Using the last expression you can clear the value of x (the smallest number)
x=2 → The smallest number of the set of three is 2
Now using this value and the given equivalencies we can calculate the midle and greatest number:
Middle number
x+3= 2+3= 5
Greatest number
4x=4*2=8
The set of three numbers is (2, 5, 8)