Question 264541
If he had $10,000 and gained 'x' dollars, then lost twice that at 2x dollars, then he would then have {{{10000+x-2x=10000-x}}} dollars. Set this equal to 6,000 to get {{{10000-x=6000}}}. Now simply solve for 'x' to find out how much he gained. Double that figure to find out how much he lost.