Multiple questions! Need help within the hour!

(if f(x)=4x^2 and g(x)=x+1, find (f o g)(x)

You and a friend race across a field to a fence and back. your friend has a 50-meter head start. the equations shown represent you and your friend's distances dd (in meters) from the fence tt seconds after the race begins. find the time at which you catch up to your friend. you: d=∣−5t+100∣d=∣−5t+100∣ your friend: d=∣−313t+50∣∣

Which expressions are equivalent to -6 + 3m