Convert the feet to inches: 1.7 feet=12*1.7 inches=20.4 in. Now the dimensions of the box are all in the same units. The volume of the box is 19*20.4*6 cubic in=2325.6 cu in.=1.3458 cu ft. (1728 cu in = 1 cu ft). The surface area is the sum of the areas of all 6 sides. There are 3 pairs of areas where each member of each pair has the same size as its partner. So that gives us the sum: 2(19*20.4+19*6+6*20.4)=2*624=1248 sq in. or 8.667 sq ft. (144 sq in = 1sq ft).
The question doesn't specify what you need to find, so I've assumed it's volume or surface area.