Which line is wrong?

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?

Out of $20$ creepy-crawly creatures in a room, $80\%$ are flies and $20\%$ are spiders. if $s\%$ of the total legs belong to spiders, what is $s$?

The box plots show the average speeds, in miles per hour, for the race cars in two different races. which correctly describes the consistency of the speeds of the cars in the two races?