When we observe a distant galaxy whose photons have traveled for 10 billion years before reaching Earth, we are seeing that galaxy as it was when the universe was:.
a) 10 billion years old.
b) 7 billion years old.
c) 4 billion years old.

a) 10 billion years old.

Explanation:

We see things only when the light from the source hits our eyes. So, if the light which has been received by our eyes has been traveling for 10 billion years then we are actually seeing the galaxy which is 10 billion years old. The galaxy is 10 billion light years away.

Therefore, the answer is a) 10 billion years old.

answer:   you might love summer weather, but you don’t want it to feel like the sun is inside your car. but a hot car that just won’t seem to cool down might be a bigger of a problem than you think. your car relies on being at the right temperature.

explanation:

distance = 150m

displ = root (50 ^2 + 100^2)

root(2500+10000)

root 125000