The expected profit when playing the $5 pair plus bet in three-card poker is \(-\$0.10\).
First, calculate the number of hands played in 4 hours.
\[35 \text{ hands/hour} \times 4 \text{ hours} = 140 \text{ hands}\]
Next, multiply the number of hands by the expected loss per hand.
\[140 \text{ hands} \times -\$0.10 = -\$14.00\]
If you play the game for 4 hours with an average of 35 hands per hour, you would expect to lose \(\$14.00\).