Can ya help me with these questions?

Lilianna uses 3/4 calories per minute just by sitting. she uses 1 more calorie per minute by walking. lilianna uses a total of 12 1/4 calories walking to the park. lilianna uses the equation, d(.75+1)=12.25 to represent the situation. what does the variable d represent in the equation?

Suppose i flip two identical coins. what is the probability that i get one head and one tail?

Icould really use some with this question.