assuming: number of coins Andrew has=a, number of coins Bob has=b, number of coins Casey has=c
Andrew has six fewer coins than Casey, so, c-6=a, or a+6=c
Bob has two more than twice as many coins as Andrew, so 2a+2=b
Together, there are 544 coins: a+b+c=544. Rewrite the equation in terms of a: a+(2a+2)+(a+6)=544. Combine like terms: 4a+8=544. Solve the equation: 4a=536, so a=134. If b=2a+2, then b=2(134)+2=268+2=270.
Bob has 270 coins.
