PLEASE ANSWER QUICK !!!!

Mikayla is determining the actual
distance between Harrisville and Lake Town
using a map. The scale on her map reads
1 inch = 50 miles. She measures the distance
to be 4.5 inches and writes the following
proportion:
1 in. 50 mi
x mi
4.5 in.
P
Explain why her proportion is equivalent to
50 mix mi
1 in. 4.5 in."