<s>[INST] What is the fastest public transit to take from Davis Square to Harvard Square? [/INST] The fastest public transit from Davis Square to Harvard Square is the MBTA Red Line. It should take approximately 8 minutes to reach the Harvard station from Davis.</s>\ <s>[INST] How much would that cost? [/INST] The Price of the One-Way of the Massachusetts BayTransportation Authority MBTA costs $2.40
with CharlieCard, CharlieTicket, or Cash. and $1.10 with reduced fare card 1-Day Pass

There is also the option of 
$11.00

Unlimited travel for 24 hours

CharlieCard and CharlieTicket valid on:
 Subway
 Local Bus
 Silver Line

7-Day Pass

$22.50

Unlimited travel for 7 days.

$90.00

Unlimited travel for 1 calendar month

This information was found in the official MBTA website https://www.mbta.com/fares/</s>