Lucy has one half hour to decorate a dozen cupcakes for a bake sale . how much time can she spend on each cupcake

Lucy has 30 minutes to decorate 12 cupcakes. she can spend 2 minutes and 30 seconds on each cupcake. this is because 30/12= 2.5 which is equal to two minutes and thirty seconds. she spend two minutes and thirty seconds decorating each cupcake.

(1/2 hour/ 12 cupcakes)* (60 minutes/ 1 hour)= 2.5 minutes/ cupcake.
(Note that the unit cancels out so you get the answer)

Lucy can spend 2.5 minutes on each cupcake~