Question

Which equation matches the statement ñThe product of 3 and the difference of a number and 10 is 15?"

Answer 1

Go by parts:

the product of 3 and the difference of a number and 10

   -> the difference of a number and 10: x - 10
   -> the product of 3 and the amount written above: 3(x - 10)

... matches 15

   -> 3(x - 10) = 15

That is option C.