1. **State the problem:** We are given pairs of letter pairs and numbers: KL : MN :: OP : ? with numbers 66, 91, 120, and options for the missing pair and number. 2. **Analyze the given pairs:** - KL corresponds to 66 - MN corresponds to 91 - OP corresponds to 120 - The missing pair corresponds to one of the options QR or PQ with numbers 153, 160, 150, or 162 3. **Identify the pattern in numbers:** Look at the numbers associated with the letter pairs: - KL = 66 - MN = 91 - OP = 120 Check the differences: - 91 - 66 = 25 - 120 - 91 = 29 The differences increase by 4. 4. **Predict the next number:** Next difference should be 29 + 4 = 33 So, next number = 120 + 33 = 153 5. **Check the options:** Only option A has 153 with QR. 6. **Confirm the letter pattern:** Pairs are KL, MN, OP, QR. Each pair moves forward by 2 letters in the alphabet: - K(11), L(12) - M(13), N(14) - O(15), P(16) - Q(17), R(18) So QR fits the pattern. **Final answer:** QR : 153