How does solar angle affect the surface temperature of earth?

independent variable?
dependent variable?

for science my bad

What role did the waterways of europe play in development of europe's economy

Geologists know that potassium-40 decays to argon-40, with a half-life of 1.3 billion years. if an analysis of a feldspar crystal in a sample of granite shows that 75 percent of the potassium-40 atoms have decayed to form argon-40, what is the age of the granite

What does 2[tex] {2}^{ - 4} \times {2}^{ - 2} [/tex]