Answer:
5cm
Explanation:
Since we know that the two corners are congruent, then if we have one side of a shape the opposite will be congruent.
We know that for the larger triangle one side is 32 cm and the opposite if 4 cm. 32 cm / 4cm = 8cm.
x is opposite of 40 cm, so we do 40cm/ 8cm = 5cm.
It was kinda hard to explain but hope this helped at least a little bit.