The angle of YWZ is equal to the angle of YWX, and angle WYX is also a right angle due to the congruency of segments WZ and WX.
Every triangle has an angle total of 180 degrees, so angle WXY is equal to
180 - (WYX + YWX)
180 - (90 + 17)
73
Angle WXY has an angle value of 73 degrees.
45 min. - 4 peoples - 5 walls
? min. - 6 peoples - 4 walls
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180 min. - 1 man - 5 walls ⇒
36 min. - 1 man - 1 wall ⇒
6 min. - 6 peoples - 1 wall ⇒
24 min. - 6 peoples - 4 walls (answer)