What are the chances of two individuals having a child with tay-sachs if the father is an ashkenazi carrier and the mother is a french-canadian carrier?

The formula that we will be using to solve this problem is:[Likelihood of mom being a carrier] * [Likelihood of dad being a carrier] * [Likelihood of having an affected child if both parents are carriers]So plugging in the values: (1/30) * (1/300) * ¼ = 2.77 * 10 ^ - 5