Explain how you can find the missing number in 3 4/5 / x = 2 5/7

(I believe I did it correctly, but you might need to double check)
assuming that the question is 

34/5 /x = 25/7 

you have to isolate x to find its value. 

so, to get rid of the denominator in the first fraction by multiplying 34/5 x x/1 (it is the same as division of fractions) 
then you get: 34x/5 = 25/7 

then, you would have to get rid of the denominators by multiplying both sides by 5 and 7, which will give you 
238x = 125. 

and then to get x, you divide 125 by 238. It isn't a nice number but that's how I did it. 

The answer will be y=-5+0 because the slope is -5 and the it has to go through y-axis 0