Answer :
x represents the number that would be added to the silver cars.
x/40= 4
X=40x4
x=160
Subtract the given 20 from 160 because 160 is the total number
160-20=140
Therefore 140 would be added to 20 silver cars to get the ratio1:4
x/40= 4
X=40x4
x=160
Subtract the given 20 from 160 because 160 is the total number
160-20=140
Therefore 140 would be added to 20 silver cars to get the ratio1:4