Answer is 40km
Explanation: 
So in this question we can use a proportion 
Since
28km is 70% we can write it equal to 70%
 28=70 
and since 100% is unknown we can write it equal to x
100=x
Then we put it in proportion form
28/x=70/100
Then cross multiply and divide 
28(100)/70=x
Which would equal 40 
        
             
        
        
        
3.96666666667 so technically it .96
        
             
        
        
        
Answer:
25%
Step-by-step explanation:
100%-30%=70%
70%-45%=25%