Answer: the number of new light bulbs that they put in is 36
Step-by-step explanation:
The Marino's put new light bulbs in all the fixtures the new house.
Each fixture used 2 light bulbs and each room had 3 fixtures. This means that the number of bulbs in each room would be 3×2 = 6 bulbs.
The new house had 6 rooms. This means that the total number of bulbs in 6 rooms would be
6 × 6 = 36 bulbs