Step-by-step explanation:
This figure is not the best, but I'll try my best here
Since BC is parallel to BE (BC is part of BE) and BA is part of BD, two sides are parallel, making two angles congruent and the triangles therefore similar.
Since BA correlates to BD (they are parallel), we can use the knowledge that BA is 7 and BD is 42 to find the scaling factor to be 42/7 =6 from ABC to DBE. Since BC correlates to BE, BC = 10, and the scaling factor is 6, BC*6=BE= 60 = height
