Question

(25x^2+4-30x)-(9x^2+4-12x)

Answer 1

Distribute the -1 to all terms in the second polynomial:
25x^2+4-30x-9x^2+4(-1)-12x(-1)

Simplify:
25x^2-9x^2+4-4-30x+12x

Answer:
16x^2-18x

Answer 2

16x² - 18x

Explanation:

(25x² + 4 - 30x) - (9x² + 4 - 12x) ← distribute this parenthesis by - 1

= 25x² + 4 - 30x - 9x² - 4 + 12x ← collect like terms

= (25x² - 9x²) + (4 - 4) + (- 30x + 12x)

= 16x² + 0 + (- 18x)

= 16x² - 18x