You can calculate the width of the lake using a surveying technique, as shown in the diagram. Find the width of the lake.

Step-by-step explanation:
Angles XVW and XYZ are congruent, and so are angles VWX and XZY by the alternate interior angles theorem.
This means that triangle VWX is similar to triangle YZX.
So, since corresponding sides of similar triangles are proportional, VW/XY = WX / XZ.
120/8 = 15 = WX / 6.
So the width is 90 m.