In 3 years, 25% of a radioactive element decays. what's it's half-life?

Click on the y intercept. -x +4 i know you cant click on it so could you just say the coordinates like (example - (1,0) you so much.

Both the red and blue line segments stretch from the center of the circle to a point on the circle. the length of the blue segment is 5. how long is the red line segment?

The number of branches on a tree demonstrates the fibonacci sequence. how many branches would there be on the next two levels of this tree? 13 | | | m branches