Answer:
4
Step-by-step explanation:
First, we can take two triangles -- one with 2 as a side and the big one. Literally every side of the triangle with the 2 in it is parallel to its corresponding side the big triangle. Therefore, we can say that the two triangles are similar.
In similar triangles, we can say that the ratios of corresponding sides are the same. Let's say that the bottom side of the big triangle is x, and the question mark is y. Therefore, the hypotenuse of the big triangle is 6+y. Furthermore, the ratio of corresponding sides ((6+y)/y and x/2) are equal, so
(6+y)/y = x/2
Since x is clearly made up of 3 and 2, we can say 3+2=x=5
(6+y)/y = 5/2
multiply both sides by y to remove a denominator
6+y = 5*y/2
multiply both sides by 2 to remove the other denominator
12+2y = 5*y
subtract both sides by 2y to isolate the y and its coefficient
12 = 3y
divide both sides by 3 to isolate the y
y=4
