Combine the terms that can be combined. Indicate the others in descending powers of x or a.

1.
[tex]25a + \: 6a^{2} - \: 3b^{2} \: + \: 6 = [/tex]
2.
[tex]3a \: + \: 2b \: - \: 3a \: + \: 1 \: - \: 3 = [/tex]
3.
[tex]3x^{2} \: - \: 2xy \: + 4x^{2} \: - \: 3xy \: + \: y^{2} = [/tex]
4.
[tex]2x \: + \: x \: + \: 25y \: - \: y \: - \: 4 = [/tex]
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