The first thing you should know is that the rate of each one is: Kaitlyn = 1/6 Mark = 1/8 Then, d = number of days. The equation then if they work together is: 1 / 6d + 1 / 8d = 1 answer: the equation for number of days it would take to build the sheld together is 1 / 6d + 1 / 8d = 1