Value for x^2 left for 95% confidence interval when n=18

In the diagram, points d and e are marked by drawing arcs of equal size centered at b such that the arcs intersect ba and bc. then, intersecting arcs of equal size are drawn centered at points d and e. point p is located at the intersection of these arcs. based on this construction, m , and m

Solve the formula ax+ by = c for x.

Is ofat (-25, 0), (25, 0) co- (0, -15), (0, 15)?