Math lol Using the formula d = r t , which of the following statements is not true?

If r = 5 and t = 3, then d = 15.
If r = 3 and t = 5, then d = 8.
If r = 3 and t = 4, then d = 12.
If r = 4 and t = 2, then d = 8.

The system of equations graphed below has how many solutions? y = 2x + 2

The ratio pv to nrt is plotted against pressure for ch4 at 0°c and 200°c. why does the curve for 0°c drop below the horizontal line for an ideal gas whereas the curve for 200°c does not?

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters