Given,
The line L pass through the point (0,1,2), intersect the line 2x−1=3y−2=4z−3 and be parallel to the plane 2x+y−3z=4,
Now plotting the diagram of above data we have,

Now let the direction of line which passes through (0,1,2) be (a,b,c)
Now the line L&{L}_{1} are coplanar,
So coplanar condition we get,
∣a2−12b3−23c4−34∣=0
⇒∣a12b13c14∣=0
⇒a−2b+c=0.......(1)
And the line L is perpendicular to the normal vector of the plane,
So by perpendicular condition we get,
2a+b−3c=0......(2)
So, from equation (1)&(2) we get,
a=b=c
So, equation of line L will be,
⇒L=1x=1y−1=1z−2=λ
So any point on L can be taken as A(λ,1+λ,2+λ),

Now AP will be perpendicular to the direction ratio of the line L,
So, again by perpendicular condition we get,
AP⋅(i^+j^+k^)=0
⇒λ−1+λ+10+λ=0
⇒3λ+9=0
⇒λ=−3
Hence,A(-3,-2,-1)&P(1,-9,2)
So, by distance formula we get, AP=74