1Write the eqn of the line to be (y-5) = m(x-2)
now the eqn of the two rays of light incident on the line 2 x + y = 1 are _|_ to each other in case the angle is 450.
m' = (m+1)/(1-m), (m-1)/(1+m)
Also, tan 450 = (m-2)/(1+2m)
Now, u can solve it.......