Which one of the following pairs is not correctly matched?

Formulas Used:}
​$$a^3 + b^3 = (a+b)^3 - 3ab(a+b)$$​​
$$a^3 - b^3 = (a-b)(a^2 + ab + b^2)$$​
​$$(a-b)^2 = (a+b)^2 - 4ab$$​​
Solution:
(a)

​$$\begin{aligned}a^3 + b^3 &= 8^3 - 3(10)(8) \\&= 512 - 240 = 272 \\\text{Correct}\end{aligned}$$​​
(b) 
​$$\begin{aligned}(a-b)^2 &= (a+b)^2 - 4ab \\16 &= (a+b)^2 - 8 \\(a+b)^2 &= 24 \\a^2 + ab + b^2 &= 24 - 2 = 22 \\a^3 - b^3 &= (4)(22) = 88 \neq 80 \\\text{Incorrect}\end{aligned}$$​​
(C) 
​$$\begin{aligned}x &= a-10,\ y=b-5 \\x+y &= (a+b)-15 = 0 \\y &= -x \\x^3 + y^3 &= x^3 + (-x)^3 = 0 \\\text{Correct}\end{aligned}$$​​
(D) 
​$$\begin{aligned}(a-b)^2 &= 225 - 56 = 169 \\a-b &= 13 \\\text{Correct}\end{aligned}$$​​
Correct answer is (B).