A farmer harvested 35 acres of corn and 20 acres of beans. Animals ate 1/8 of the corn he originally planted. how many acres of corn did the farmer plant?

now..... we're assuming here, that the farmer planted "more than 35 acres" of corn, so, he planted some amount of corn, but he only harvested a fraction of it, which is 35 acres, and we're assuming he gave those 35 acres of harvested corn to the livestock, so the animals ate 1/8 of the corn he planted.

That means, if the animals ate 1/8 of the corn, and the farmer gave the animals the whole of the harvested corn, then we can say that the 35 acres is just 1/8 of what he planted.

now, if 35 is 1/8, what is the whole?  namely 8/8?

[tex]\bf \begin{array}{ccll} \stackrel{corn}{amount}&\stackrel{corn}{fraction}\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 35&\frac{1}{8}\\\\ c&\frac{8}{8} \end{array}\implies \cfrac{35}{c}=\cfrac{\quad \frac{1}{8}\quad }{\frac{8}{8}}\implies \cfrac{35}{c}=\cfrac{1}{8}\cdot \cfrac{8}{8} \\\\\\ \cfrac{35}{c}=\cfrac{1}{8}\implies 280=c[/tex]