Since we need to find the point at which the 2 lines intersect at the x-axis, we need to find where the 2nd line intersects the x axis, by plugging in y=0.
x-2(0)=4
x=4
Therefore, at (4,0).
Now we plug in (4,0) at the first equation.
4b+3(0)=10
4b=10
b=5/2
Therefore, at b=5/2
