I do this one and leave the other as excersises.

How many ways are there of choosing 3?

In total we have 3+6+1=10.

Thus, 10C3=120

How many ways of choosing 1 white, 1C1=1

Similarly, red: 3C1=3 and blue: 6C1=6.

Thus, there are (1)(3)(6)=18 different ways of choosing red,white and blue.

The probability therefore is,

18/120=3/20=15%