Kent 18-Speed Full Suspension Mountain Bike

All 3 bikes are relatively old. Children’s bikes 30$ Grey bike Hogback mountain bike featuring an 18-speed drivetrain and full suspension - works completely fine, chain, wheels, breaks everything is good 20$ - Purple bike works fine- everything is fine EXCEPT the breaks, needs a quick tightening 10$ - Red bike, everything works no issues 50$ for all 3 bikes