Any one online that can talk with me( I'm a boy and 13)

What percentage of the earth's water is available for use by living things?

The equation 24x2+25x−47ax−2=−8x−3−53ax−2 is true for all values of x≠2a, where a is a constant.what is the value of a? a) -16b) -3c) 3d) 16

Give 2 examples of the sedimentation in the deep ocean?