c₁₆ - a₁₆ = 12 - 10 = 2₁₆
7 < c = 12 in base 16, so borrow 1 from the next place value:
17₁₆ - c₁₆ = 23 - 12 = 11 = b₁₆
In the next place, we replace 5 with 4, but 4 < 6, so borrow 1 from the next place value again:
14₁₆ - 6₁₆ = 20 - 6 = 14 = e₁₆
Replace d with c, so that
c₁₆ - 7₁₆ = 12 - 7 = 5₁₆
and this gives
d57c₁₆ - 76ca₁₆ = 5eb2₁₆