(See attached diagram.) The positions of the vaulter's left and right hands are marked. The length of the entire pole is 15 feet. The segment below her left hand is twice as long as the segment above, so label those two parts with x and 2x. Those two segments add up to 15 feet:
The lower segment is 10 feet long. The vaulter's right hand is 1.5 feet above her left, so it is 10 + 1.5 = 11.5 from the bottom of the pole.