To solve this expression, we must first simplify each term separately and then add them together.

5/12 • 2/3/7 = (5/12) * (2/21) = 10/252 = 5/126

5/12 • 3/4/7 = (5/12) * (3/28) = 15/336 = 5/112

Adding these two terms together:

5/126 + 5/112

To add fractions, we need to find a common denominator, which in this case is 126 * 112 = 14112.

Now we convert both fractions:

5/126 = 560/14112
5/112 = 630/14112

Adding them together:

560/14112 + 630/14112 = 1190/14112

Therefore, the final answer is 1190/14112 or simplified as 595/7056.