(3.2b+0.8)+1.9b simplify the expression. explain each step

Choose the triangle with x equal to 17.

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∣∣

What is the length of the unknown leg in the right triangle ?