Answer:
answer is 20
we know that,
perimeter of a triangle =all sides of triangle.(ie.A+B+C)
LIKEWISE..
perimeter of 1st triangle
=5+x-5+x-4
=2x-4
again,
perimeter of 2nd triangle
=16+10+x-10
=16+x
now according to question
perimeter of 1st triangle =perimeter of 2nd triangle
2x-4=16+x
2x-x=16+4
therefore ...x=20
