This is hard for me but easy for you so what’s the answer ?

According to modern science, earth is about 4.5 billion years old and written human history extends back about 10,000 years. suppose the entire history of earth is represented with a 10-meter-long timeline, with the birth of earth on one end and today at the other end.

If cos(2x) = tan^2(y), show that cos(2y) = tan^2(x).

Which number line correctly shows 0.8 + 0.3?