Could I have assistance in determining the value of X for this triangle? I don’t understand it at all.

Answer:
35
Step-by-step explanation:
The triangle side lengths are proportional to each other, and we have 2 sides in the ratio 30 : 25 or 6 : 5.
A side length of 42 means that x must be equal to 42 x 5/6 = 35