If Paul can decorate 3/4 of a cupcake per minute then:
3/4 x 12/1 because if you can decorate 3/4 a cupcake per minute, you multiply 3/4 by 12 to find the total amount of cupcakes he could decorate.
3/4 x 12/1 = 9
Paul can decorate 9 cupcakes in 12 minutes.