Maria Rivera can walk 3 1/2 in one hour at this rate how far can she walk in a half hour

Question

explain for me to understand 

Answer 1

set up a proportion

 

3.5 miles             X miles

________     =   __________

   1 hr                  0.5 hrs

 

cross multiply

 

(3.5)(0.5)   = X

 

X = 1.75 miles