Answer:
PQ = 37 Km
Explanation:
let PQ = x , then
PR = x + 15 and QR = 3(x + 15) = 3x + 45
sum the parts and equate to 245
x + x + 15 + 3x + 45 = 245 , that is
5x + 60 = 245 ( subtract 60 from both sides )
5x = 185 ( divide both sides by 5 )
x = 37
then
PQ = x = 37 Km