[A].

If Conner used t minutes on talking on the phone, then at 6 cents/min, he spent t*6 = 6t cents.

If he used g minutes on playing games on the phone, at 3 cents/min, he spent g*3 = 3g cents.

He has $18 or 1800 cents to spend, so

6t +3g = 1800 ---------------------------(1)

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[B].

If he plays for 5 hrs,

5hrs *60min/hr = 5*60 = 300 minutes,

then g = 300 min.

Substitute that into (1),

6t +3(300) = 1800

6t = 1800 -900

6t = 900

t = 900/6 = 150 min

150min *1hr/60min = 150/60 = 2.5 hrs or 2hrs and 30min.

Therefore, Conner can talk for 2 hours and 30 minutes with the $18 he has.