Concept:Find the unknown value by using percentage calculation and simple subtraction.Explanation:Let the missing number be x.The equation is 13% of 258−x=10.First, calculate 13% of 258.13% of 258=10013​×258.=33.54.Now substitute back: 33.54−x=10.So, x=33.54−10.x=23.54.This matches option C.Answer:23.54