Let's simplify the given expression step by step:

(6c + d) • (8c - 9d) = 6c • 8c - 6c • 9d + d • 8c - d • 9d
= 48c^2 - 54c + 8cd - 9d^2

(-10d + 2c) • (11c - 4d) = -10d • 11c + 10d • 4d + 2c • 11c - 2c • 4d
= -110cd + 40d^2 + 22c^2 - 8cd

Now, combining the two results:

(6c + d) • (8c - 9d) + (-10d + 2c) • (11c - 4d) = 48c^2 - 54c + 8cd - 9d^2 - 110cd + 40d^2 + 22c^2 - 8cd
= 70c^2 - 62c - 102cd + 31d^2

Therefore, the simplified expression is 70c^2 - 62c - 102cd + 31d^2.