Answer:
πr^
radius = 10 inches
π X 10^
314.159265
314.16 cm^
27.7-14=Cost above 500 msg
13.7=C
E=number of Extra messages sent
C=0.1E
13.7/0.1=E
137=E
Total messages=T
T=500+E
T=500+137
T=637
Danielle sent 637 messages in September
