To answer this question, we need to know that as Zachary employs more hours in preparing kilograms of dough, he will obtain more kilograms of dough. Then, if Zachary prepares 15 kg of dough after working 3 hours, he will obtain more kilogram after working 4 hours.
Therefore, we have:
![\frac{x}{15\operatorname{kg}}=(4h)/(3h)\Rightarrow x=\frac{4h\cdot15\operatorname{kg}}{3h}\Rightarrow x=20\operatorname{kg}]()
We can see that after 4 hours, we can expect that Zachary will prepare 20kg of dough in 4 hours.
We can also