Triangle HAM looks like an isosceles triangle, and we know that in an isosceles triangle 2 of the angles are the same.
so :
180 - 106 = 74 ( sum of the other 2 angles )
74/2 = 37 ( sum of angle HMA / HAM )
angles on a straight line add up to 180.
180-37=143 ( angle x )
since triangle YMH is also an isosceles,
180-37=143
143/2=71.5 ( angle w )
10•8=80
so something times 80 will equal 400
80•5=400
Y=|x-7| because in order to go to the right you have to subtract the amount from x