The replacement set for an equation is {8,9,12,18}.
 The equation is represented by the sentence, "23 of a number is 12."
 What is the solution set of the equation?
 Responses
 {8} 
 open curly bracket 8 close curly bracket, 
 {9}
 open curly bracket 9 close curly bracket
 {12}
 open curly bracket 12 close curly bracket
 {18}