90 ones would make 9 tens. It makes 9 tens because theres a 0 after 90. The 0 represents another place value. You can write this as 9 groups of ten
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5 red, 3 blue, 7 white.....total of 15
probability of 1st drawn being red : 5/15 reduces to 1/3
without replacement
probability of 2nd being red : 4/14 reduces to 2/7
probability of both : 1/3 * 2/7 = 2/21 <==
