2.4 + 5.6 (13 3/4 - 12 13/14)
= 2.4 + 5.6 (55/4 - 191/14)
= 2.4 + 5.6 (55/4 - 13 3/4)
= 2.4 + 5.6 (55/4 - 55/4)
= 2.4 + 5.6 * 0
= 2.4

Therefore, 2.4 + 5.6*(13 3/4 - 12 13/14) = 2.4.