He simplified expression C because that is the only one that has only multiplications.
To solve this you can make a perportion
252 x
----- = -----
350 100
and solve 252 times 100/350=72
252 is 72% of 350
Is there a picture that goes with the question ?
Well

translates to

so
log5(x/2)=5 means 5^5=x/2, so 3125=x/2, so 6250=x
Answer:
The transformation is rigid because the corresponding side lengths and angles are congruent.
Step-by-step explanation:
Since we have congruent triangles (not similar triangles), they will have to have the same length and angles throughout your transformation. Therefore, our answer is the 1st Option.