Help please :( help me :)

Which three lengths could be the lengths of the sides of a triangle? 21 cm, 7 cm, 7 cm 9 cm, 15 cm, 22 cm 13 cm, 5 cm, 18 cm 8 cm, 23 cm, 11 cm

You can ride your bike around your block 6 times and the whole neighborhood 5 times in 16 minutes. you can ride your bike around your block 3 times and the whole neighborhood 10 times in 23 minutes. how long does it take you to ride around the neighborhood?

Will mark ! (10 points also! ) if x varies inversely with y and x =6 when y= 10, find y when x=8 a. y=4.8 b. y=7.5 c. y=40/3 d. y=4/15