How do I make a rational equation with: If Beth takes one hour to bake a cake and it takes her daughter, Sally, an hour and 30 minutes to bake a cake, how long would it take for Beth and Sally to bake a cake together?

Question

anonymous · Answer

lets call one hour and 30 minutes one and a half hours or better yet $\frac{3}{2}$ hours

anonymous · Answer

then together they can bake the cake in 
$$\frac{1\times \frac{3}{2}}{1+\frac{3}{2}}$$ hours

anonymous · Answer

we can take the steps if you like