Answer:
10
Step-by-step explanation:
Pabp = AB +BP +AP
Papc = AP +PC +CA
So the sum of perimeters of the two smaller triangles is ...
Pabp +Papc = AB +BP +AP + AP +PC +CA
= (AB +BP +PC +CA) +2AP
= Pabc +2AP
Filling in numbers, we have ...
30 +35 = 45 +2AP
20 = 2AP . . . . subtract 45
10 = AP . . . . . . divide by 2
The length of AP is 10 units.
