Use the substitution method to solve the system of equations. choose the correct ordered pair. x + y = 11 –x = –y – 9 a.(9, 2) b.(10, 1) c.(11, 0) d.(8, 3)

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.

For the inequality |c| < |d| to be true, which of the following must be true?

Which of these figures must be a rectangle?