Rafael writes an expression to represent “a number, n, decreased by thirty-one.” then he evaluates that expression if n=29. which statements are true about the expression and its evaluation? check all that apply. a. the correct expression is 31-n. b. this is a subtraction expression. c. this is an addition expression. d. to evaluate, substitute 29 for the variable in the expression. e. to evaluate, substitute 31 for the variable in the equation. f. to evaluate the expression, add 31 to 29. g. the correct expression is . h. to evaluate the expression, subtract 31 from 29.