Silvia is growing trees and studying their heights. Her data is shown below. Tree type Height (meters) Birch 3 \dfrac{1}{4}3 4 1 3, start fraction, 1, divided by, 4, end fraction Spruce 2 \dfrac{7}{8}2 8 7 2, start fraction, 7, divided by, 8, end fraction Oak 3 \dfrac{1}{2}3 2 1 3, start fraction, 1, divided by, 2, end fraction What is the difference between the heights of the birch and spruce trees?