The area of a triangle formula is A = 0.5*b*h where b is the base and h is the height. To solve for b, we multiply both sides by 2 to get 2A = b*h and then we divide both sides by h to get b = 2A/h. Now plug in the given info to get...
b = 2*A/h
b = 2*36/6
B = 72/6
b = 12
so if the area is 36 and the height is 6, then the the base must be 12