Hey

You need to find the probabilities first

p("three red") =

p("one blue") = prob(blue,red,red)+p(red,blue,red)+p(red,red,blue)

(I hope in this formula is no typo in it)

p("three blue") = p(blue,blue,blue)

I think you can solve it yourself

and then E(x) = -10*p(three red) + 10*p(one blue) + 20*p(two blue)+30*p(three blue)

Rapha