You can use Desmos Graphing Calculator to graph but here's the answer.
Answer: $50
Step-by-step explanation:
250 x 0.20 = 50
$50 discount
or you pay 80%, so
250 x 0.80 = 200
$200 final cost
$250 original cost - $200 final cost = $50 discount
(19+7):(2*6+1)=26:(12+1)=26:13=2
pi times radius equals the area of a circle
Ratio of shadow to object's size = 2/7
Then, size of tree would be: 7/2 * 28 = 7 * 14 = 98 feet
So, your final answer is 98 feet
Hope this helps!