28)  Divide:  

12) Simplify:  

At this time, approximately how much of the world’s electrical production comes from solar and wind?

At this time, approximately how much of the world’s electrical production comes from solar and wind?

What effects can the removal of the canopy in a rainforest have?

What effects can the removal of the canopy in a rainforest have?

Most genetic mutations are the result of:

What do we call a relationship between two types of organisms, which often benefits both?

Most genetic mutations are the result of:

Currently, Americans are responsible for making about what percent of the total global greenhouse gases produced by humans?