Answer:
4 hours
Step-by-step explanation:
First, create a linear equation for Carlos using the graph.
Two points on the line: (0, 2) and (1, 10)
[tex]\implies \sf slope\:(m)=\dfrac{change\:in\:y}{change\:in\:x}=\dfrac{10-2}{1-0}=8[/tex]
Use the point-slope equation with the found slope and one of the points:
[tex]\implies y-y_1=m(x-x_1)[/tex]
[tex]\implies y-2=8(x-0)[/tex]
[tex]\implies y=8x+2[/tex]
Now equate the equations for Mary Ann and Carlos, and solve for x:
[tex]\implies 6x+10=8x+2[/tex]
[tex]\implies 8=2x[/tex]
[tex]\implies x=4[/tex]
Therefore, Mary Ann and Carlos have saved the same amount after 4 hours work.