Explain what is causing these balloons to push each other away.

The ballon has a negative charge. They will attract each other because opposite charges attract. On the other hand, two charged balloons repel each other. Each has a negative charge, and charges that are the same repel one another.

I hope this helps!

28. evolution

29. environment, survive, offspring  

explanation:

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west