Compared to Liam, Billy had 80% fewer candy bars. Billy had 2/3 as many chocolate bars as Liam after receiving 315 from Liam. How many chocolate bars total did they each end up with?
Let X be the total number of chocolate bars Liam had
Billy had 2X/3 + 315 after receiving 315 from Liam
Billy had 2X/3 chocolate bars before receiving 315 from Liam
Billy had X - 315 chocolate bars after giving 315 to Liam.
Billy had X - (80/100 * X) chocolate bars initially
X - 315 = 2X/3
3X - 945 = 2X
3X - 2X = 945
X = 945 chocolate bars Liam had
Billy had X - 315 = 945 - 315 = 630 chocolate bars
In total, they had 945 + 630 = <<945+630=1575>>1575 chocolate bars. Answer: \boxed{1575}.