Question

A bag contains 7 blue coloured balls, 8 yellow coloured balls and 5 green coloured balls. in how many ways can three balls be picked from the bag so that we get balls of exactly two different colours?

Answer 1

b=7
y=8
g=5
results are
byg, bgy,ybg, ygb, gby, gyb,Bbyy,gyy,BY, bbg,yyb, yyg,