x= -2 (-5 + t) (1)
y= 5 + t (2)
t = y - 5;
Substitute into (1)
y = -(1/2)x + 10
ContourPlot[x^2 + y^2 == 25 , y == -(1/2)x + 10]
You can also try the reverse and change to parametric. That could be left as an exercise.
... -> Edit chart -> Customize -> Gridlines -> Horizontal Axis (in
drop down) -> Major gridline count
Under the Major gridline count you can select or type however many dates you want to see on the horizontal label here, for auto mine shows up with a reasonable number of dates but if you wanted to see 20 dates or 10 dates you can type 20 or 10 ...