Answer:
x = 11
Step-by-step explanation:
right triangle ABC
using Pythagoras' identity
BC² = 7² + 24² = 49 + 576 = 625 ( take square root of both sides )
BC = = 25
Since the triangles are congruent then corresponding sides are congruent.
ST = BC , that is
3x - 8 = 25 ( add 8 to both sides )
3x = 33 ( divide both sides by 3 )
x = 11