Identify Two Appropriate Variables, and Use the Variables to Write $40$

Multiple Choice

Identify two appropriate variables, and use the variables to write equations. Use either the elimination method or the substitution method to solve the equation The sum of two numbers is $40$ _. There difference is $6$ .
Find the numbers.

A) $23.5,16.5$
B) $23,17$
C) $18,12$
D) $25,15$
E) $26,14$