Angle R is the reference angle as its the only given angle (other than the 90 degree angle).
Opposite angle R is segment PQ
PR is the hypotenuse
Use the sine rule to find that...
sin(angle) = opposite/hypotenuse
sin(R) = PQ/PR
sin(19) = PQ/11
11*sin(19) = PQ
PQ = 11*sin(19)
PQ = 3.58124969902872 <<-- use a calculator (degree mode)
PQ = 3.58
Answer: 3.58
I think the answer might be x=4/8
Use area formula (length x width)
42 x 25.5 = 1,071
Divide by total cost of wall paper
1,071/771.25 = $1.38 per square foot