Respuesta :

63+x       x+3
-------- = -------
  36           6


63 +x = 6(x+3)

63 +x = 6x +18

63 -18 = 6x -x

45 = 5x

x = 45/5

x = 9 
if they're congruent, then their sides are in the same ratio
so

BC:BA=CE:ED
or
5:x=25:18-x
we
5/x=25/(18-x)
flop
x/5=(18-x)/25
times both sides by 25
5x=18-x
add x both sides
6x=18
divide both sides by 6
x=3