Hey there
As per question,
[tex](24x - 8y) - (7x - 20y) \\ = > (24x - 7x) + ( - 8y + 20y) \\ = > (24 - 7) \times x + ( - 8 + 20) \times y \\ = > 17x + 12y[/tex]
Therefore, 17x+12y is the answer