Tonya’s dog-walking service charges a flat rate of $20 per month, plus $3 per mile that each dog is walked. Beth does not charge a monthly fee for her dog-walking service, but she chargers $5 per mile that each dog is walked. Choose the equation that can be used to find the number of miles m for which Tonya and Beth would charge the same amount.

A. 20+3m=5m

B. 20=3m+5m

C. 20+5m=3m

D. 20+m=8m

m= miles