Answer:
? = 30
Explanation:
If the triangles are similar, then the only way I see this working is the sides measuring 63 and 54 are corresponding. The sides measuring 56 and 48 are corresponding. That leaves the sides measuring 35 and ? corresponding.
Set up a proportion.
63/54 = 35/?
63? = 54 * 35
63? = 1890
? = 30