Răspuns:
1. x - 35y
2. 6x^2 - 5xy - 6y^2
3. x + 6y - 5(64x^2 - 4y^2) = x + 6y - 320x^2 + 20y^2
4. 3 - 2xy
5. a^2bc
6. - 2
7.
20x + 25y = 105
-20x - 16y = - 60
_____________ +
/ 9y = 45 => y = 5 => x = - 1 => x - y = - 6
8.-2a - b - c
