A perendicular line will have a slope that is the negative reciprocal of the perpendicular slope. The negative reciprocal of - 1/3 is 3. So far we have y=3x+b since 3 is the new slope. However, we need to set a b value such that it passes through (1,5). Set y to 5 and x to 1. 5=3(1)+b and we can see that to satisfy this, b must be 2. Thus, the line is y=3x+2