We want to determine similar triangles.
Let us compare triangle HJI with triangle QRS
Recall, the sum of the angles in a triangle is 180 degrees. This means that for triangle HJI,
H + I + J = 180
H + 37 + 90 = 180
H + 127 = 180
H = 180 - 127 = 53
By comparing both triangles,
angle H = angle Q = 53 degrees
HI/JH = 10/6 = 1.67
QS/RQ = 1.25/0.75 = 1.67
The ratios of the corresponding sides of the triangles are equal. Thus,
Triangle HJI is similar to triangle QRS