\( \begin{array}{ll}\text { 1) }(12,20)= & M C D: \square \\ \text { 2) }(6,8)= & M C D: \square \\ \text { 3) }(10,22)= & M C D: \\ \text { 4) }(16,38)= & M C D: \\ \text { 5) }(35,85)= & M C D\end{array} \)

To find the greatest common divisor (GCD) of the pairs of numbers, we can use the prime factorization method or the Euclidean algorithm. Here, I'll calculate the GCD for each pair: 1) **(12, 20)**: - Prime factorization of 12: \( 2^2 \times 3 \) - Prime factorization of 20: \( 2^2 \times 5 \) - Common factors: \( 2^2 \) - GCD: \( 2^2 = 4 \) **GCD: 4** 2) **(6, 8)**: - Prime factorization of 6: \( 2 \times 3 \) - Prime factorization of 8: \( 2^3 \) - Common factors: \( 2^1 \) - GCD: \( 2^1 = 2 \) **GCD: 2** 3) **(10, 22)**: - Prime factorization of 10: \( 2 \times 5 \) - Prime factorization of 22: \( 2 \times 11 \) - Common factors: \( 2^1 \) - GCD: \( 2^1 = 2 \) **GCD: 2** 4) **(16, 38)**: - Prime factorization of 16: \( 2^4 \) - Prime factorization of 38: \( 2 \times 19 \) - Common factors: \( 2^1 \) - GCD: \( 2^1 = 2 \) **GCD: 2** 5) **(35, 85)**: - Prime factorization of 35: \( 5 \times 7 \) - Prime factorization of 85: \( 5 \times 17 \) - Common factors: \( 5^1 \) - GCD: \( 5^1 = 5 \) **GCD: 5** Now, summarizing the results: \[ \begin{array}{ll} \text{1) }(12,20) & \text{GCD: } 4 \\ \text{2) }(6,8) & \text{GCD: } 2 \\ \text{3) }(10,22) & \text{GCD: } 2 \\ \text{4) }(16,38) & \text{GCD: } 2 \\ \text{5) }(35,85) & \text{GCD: } 5 \\ \end{array} \]