Abcd is an isosceles trapezoid with legs ab and cd and base bc. if the length of ab is 7y - 4, the length of bc is is 4y - 6 and the length of cd is 8y - 18, find the value of y.

9.4.34  question   to estimate the height of a stone  figure, an observer holds a small square up to her eyes and walks backward from the figure. she stops when the bottom of the figure aligns with the bottom edge of the  square, and when the top of the figure aligns with the top edge of the square. her eye level is 1.811.81 m from the ground. she is 3.703.70 m from the figure. what is the height of the figure to the nearest hundredth of a  meter?