Which ratio does not belong 3: 3, 9: 12, 12: 15, 12: 16 plz answer for me

What is the first step of an indirect proof of a number that is divisible by two

Awoman has 14 different shirts: 10 white shirts and 4 red shirts. if she randomly chooses 2 shirts to take with her on vacation, then what is the probability that she will choose two white shirts? show your answer in fraction and percent, round to the nearest whole percent.

What is the best estimate of the length of a football