Answer:
7.8 (when I calculated I rounded to tenths so the actual answer might be a little bit different)
Explanation:
the area of a circle is radius squared so
153.86= radius squared
sqaure root both sides and you get 12.4 =radius
divide both sides by pi and you get 3.9 which is the radius
the diameter is double the radius which is 3.9 *2 which is 7.8 :) hope this helped.