Problems 1 and 2 deal with the predator–prey system

that corresponds to Fig. 9.3.1.

Separate the variables in the quotient

of the two equations in (1), and thereby derive the exact implicit solution

of the system. Use the contour plot facility of a graphing calculator or computer system to plot the contour curves of this equation through the points (75 , 100), (75 , 150), (75 , 200), (75 , 250),  and (75 , 300),in the xy-plane. Are your results consistent with Fig. 9.3.1?

dx dt dy dt 200x - 4xy, -150y + 2xy (1)