The United States uses about of the world's energy. 50 33 25

25%

Explanation:

America is just one of the many countries on this planet, and compared to them and the rest of Earth, America takes up a very little percentage of energy.  Although, America's energy usage levels are increasing daily.

a: 45.9 meters

b: 4.29 seconds

step-by-step explanation:

a: h(t)=1/2(-9.8)(3)^2+0(3)+90

h(t)=-4.9(3)^2+90

h(t)=-44.1+90

h(t)=45.9 meters

b: 0=1/2(-9.8)(t^2)+0t+90

0=-4.9t^2+90

-90=-4.9t^2

18.37=t^2

t=4.29 seconds

in the second question, the numbers aren't exact, but they're a close approximation.

the answers would be

the first one and the second one