The distance between Dublin and Galway is approximately 125 miles.
If you drive at a constant speed of 70 miles per hour, it will take you 125 / 70 = 1.79 hours to get to Galway.
Pausing for 30 minutes for lunch means you will add 0.5 hours to your trip.
So, your trip in total will be 1.79 + 0.5 = 2.29 hours.
Rounding to the nearest tenth of an hour, your trip will take 2.3 hours in total.