Answer
67,200 bu
Work Step by Step
Create a proportion using ratios of bu : acre.
$\frac{42000\ bu}{350\ acre}=\frac{x\ bu}{560\ acre}$
Set the product of the means equal to the product of the extremes and solve for the variable.
$350\times x = 42000\times560$
$350x=23,520,000$
$350x\div350=23,520,000\div350$
$x=67200$
