Let N be the total number of students in the college.


Then the number of girls in the college  G = 0.6*N     (1)

     the number of boys in the college   B = 0.4*N     (2)

     the number of boys studying Math    BM = 0.25*B = 0.25*(0.4*N) = 0.1*N     (3)

     the number of girls studying Math   GM = 0.1*G  = 0.1*(0.6*N)  = 0.06*N    (4)

     the number of students studying Math M = BM + GM = 0.1N + 0.06N = 0.16N    (5)


The problem question is about the ratio , i.e. the ratio (4) to (5), which is   =  =  = 0.375 = 37.5%.