1 kg=1000g*1000mg/1g=1000000mg =10⁶ mg
or you can use proportion
1000g - x mg
1 g     -1000mg
x=1000*1000=1000000mg 
1kg=10⁶ mg
        
                    
             
        
        
        
I’m not 100 percent sure someone can comment on this and confirm but when it’s written like a fraction it means division. If they gave you the meaning of each variable (the letters) multiply each variable by each coefficient (the number next to the variable). Multiply all of those. Then divide it by the product of 4 and the variable
Hope this helped!
        
             
        
        
        
Yes he has enough since 
1.7 times .9 is 1.53 which is only 153 cm