Answer:
$19
Explanation:
First you need to make a equation out of given information and this will be easiest to solve as an equation.
3.5 $66.50
1 x
-----------------------
3.5:1=66.50:x
3.5x=66.50/:3.5
x=19
On the right side you put one information(in this case number of yards) and on the left other information(cost) and you make proportion from up to down and solve for x.