Question: how to subtract in algebraic expression?
Answer: Subtract 4a + 5b - 3c from 6a - 3b + c. Solution: 6a - 3b + c. + 4a + 5b - 3c. ... 
Subtract 3x² - 6x - 4 from 5 + x - 2x². Solution: Arranging the terms of the given expressions in descending powers of x and subtracting column-wise; - 2x² + x + 5. ... 
Subtract 3x + y – 3z from 9x – 5y + z. Solution: 9x – 5y + z. + 3x + y – 3z.