In this question , it is given that
[tex] 3/4 [/tex]of Alvin's marbles are black and [tex] 1/5 [/tex]are green.
And we have to find the ratio of black marbles to the green marbles.
[tex] \frac{3/4}{1/5} [/tex]
Multiplying both numerator and denominator by 20
[tex] \frac{3*20/4}{1*20/5}= \frac{15}{4} [/tex]
So the required ratio is 15:4 .
