The vertices of ∆pqr are p(–2, –4), q(2, –5), and r(–1, –8). if you reflect ∆pqr across the y-axis, what will be the coordinates of the vertices of the image ∆p′q′r′?

A reflection around the axis and is given by the following rule:
 (x, y) > (-x, y)
 Applying the rule to each vertex we have:
 (-2, -4) > (2, -4)
 (2, -5) > (-2, -5)
 (-1, -8) > (1, -8)
 
 the coordinates of the vertices of the image ΔP'Q'R 'will be:
 P '= (2, -4)
 Q '= (- 2, -5)
 R '= (1, -8)