Let x be the number. "When 2/3 is added to a certain number" so we get x + 2/3 "The sum is 3 greater than twice that number" so it's 3 + 2x
So 2/3 + x = 3 + 2x Subtract 2/3 from both sides: 2/3 + x = 3 + 2x 2/3 - 2/3 + x = 3 - 2/3 + 2x x = 7/3 + 2x Subtract 2x from both sides x - 2x = 7/3 + 2x - 2x -x = 7/3 Multiply by (-1) to get the positive x -x = 7/3 x = -7/3
