Question

If 15Cr = 15Cr-3 then r is equal to​

Answer 1

15 is a superscript of C and 3r, r+3 are subscripts of C. If 15C3r = 15Cr+ 3 , then we follow the formula: Cx = nCy where x = y OR x + y = n. r cannot be a fraction since this will give us 1.5 therefore the answer will be r = 3.

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