28/8 = 3.5
3.5*6 = 21 km
42/6=7
7*8 = 56 miles
direct proportion y=kx , k is constant and k does not equal to 0.
17.5=k(21)
k=5/6
when x =39
y=5/6 ×39
y=32.5
WXY = XYW ( = 41 ) ⇒ XYW is a isosceles triangle
⇒ XW = YW
⇒ 54 = 6x + 6
⇒ 6( x + 1 ) = 54
⇒ x + 1 = 9
⇒ x = 8
ok done. Thank to me :>