Answer:
PF = 9
Explanation:
the incentre of a triangle is equally distant from the triangle's 3 sides, that is
PD = PE = PF
using PD = PE to solve for x
5x - 6 = 3x ( subtract 3x from both sides )
2x - 6 = 0 ( add 6 to both sides )
2x = 6 ( divide both sides by 2 )
x = 3
then
PE = 3x = 3 × 3 = 9
PF = PE = 9