Jennifer lopez met her 9 cousins at a family reunion. the number of male cousins (x) was 2 less than the number of females cousins (y)

We define the variables first:
 x = number of male cousins
 y = number of females cousins
 We write the system of equations:
 x + y = 9
 x = y-2
 We solve the system:
 Equation 1:
 x + y = 9
 (y-2) + y = 9
 2y-2 = 9
 y = 11/2 = 5.5
 Equation 2:
 x = 5.5-2
 x = 3.5
 
 Although physically it does not make sense, mathematically the answer is:
 number of male cousins = 3.5
 number of females cousins = 5.5