Amount of pizza dough that Rosa has = 4 1/2 pounds
= 9/2 pounds
Amount of dough required by Rosa to make 1 pizza = 3/4 pounds
Then
The number of pizza that can be made with 9/2 pounds of dough = 1/(3/4) * (9/2)
= (4/3) * (9/2)
= 2 * 3
= 6
So Rosa can make 6 pizzas with the amount of dough she has.
I hope the procedure is clear enough for you to understand.
Glad to have helped you.
