Help (easy points)

Just give me the answer to this

Given this information, which expression must represent the value of b?

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

Aliaa is skating down a ramp. the wheels on her skateboard have diameters of 60 \text{ mm}60 mm60, space, m, m. what is the distance aliaa travels when her skateboard wheels make 202020 revolutions? round your answer to the nearest \text{mm}mmm, m.