Решение:
- \( 10a + b - 10b - a = (10a - a) + (b - 10b) = 9a - 9b \)
- \( -8y + 7x + 6y + 7x = (7x + 7x) + (-8y + 6y) = 14x - 2y \)
- \( -8x + 5.2a + 3x + 5a = (-8x + 3x) + (5.2a + 5a) = -5x + 10.2a \)
- \( 5a + 7a - 9.2m + 15m = (5a + 7a) + (-9.2m + 15m) = 12a + 5.8m \)
Ответ: а) \( 9a - 9b \); б) \( 14x - 2y \); в) \( -5x + 10.2a \); г) \( 12a + 5.8m \).