Answer:
48
Step-by-step explanation:
If we assume that lights are put on all four sides of the rectangular deck, the perimeter length of the deck is ...
P = 2(L+W) = 2(49 ft + 23 ft) = 2(72 ft) = 144 ft
There are 3 ft in each yard, so this length is ...
(144 ft) × (1 yd)/(3 ft) = 48 yd
Robert needs 48 yards of lights.