In a drawer there are 4 blue 2 green 4 magenta shirts. If 2 shirts are drawn at random what is the probability

at least one of the shirts will be blue

There is a 4/10 chance the first shirt will be blue.
There is a 6/10 chance the first shirt will not be blue and then a 4/9 chance the second one will be blue.
These add up to 4/10 + (6/10)(4/9) = 36/90 + 24/90 = 60/90 = 2/3.

Probability that you'll get what?
The probability that you'll actually draw a shirt is 100%

But you can solve it unless it's probability of 2 green shirts, or a green and blue.

How to find your answer:
Add all # of shirts.
Put the # that you pull out, which is 2, over that # which is 10, and you have 2/10.
Simplify it.. 1/5

40% chance 4 + 2 + 4 = 10 4 out of 10 are blue. 4/10=0.40. 0.40=40%

2/10