Answer:
[tex]A(10,9)[/tex]
Step-by-step explanation:
Consider the attached figure.
The equation is [tex]y=x-1[/tex]
At [tex]x=0;y=0-1=-1[/tex]
At [tex]y=0;0=x-1,x=1[/tex]
Plot points [tex](0,-1)\,,\,(1,0)[/tex].
Marcus starts walking at the point B(0, 9) so that his path is perpendicular to Sarah's at point A.
From the graph, Sarah's path and Marcus's path intersect at point [tex]A(10,9)[/tex]