Step-by-step explanation: You calculate slope/rate of change by determining the rise over the run. The rate of change in A is 5/6x, this is bigger than the slope of B.
If the first roll is a three, then the only chance of the sum of the two numbers being less than six is if you roll a 1 or a 2. That is 2/6 chance, or simplified, a 1/3 chance.
