Question 1060029
<pre>
1. M v (D · L) 
2. B &#8835; ~(M v L)    /~B 

3. M v (L · D)           1, Commutation
4. M v L                 4, Simplification
5. ~~(M v L) &#8835; ~B        2, Transposition
6. (M v L) &#8835; ~B          5, Double negation
7. ~B                    6,4, Modus ponens

Edwin </pre>