Hi! I need help with these please, thank you!

(5 screenshots included)

The diameter of a circular chip is doubled to use in a new board game. the area of the new chip will be

Asequence is defined recursively using the formula f(n + 1) =f(n) - 5. which sequence could be

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /