10 (7k+9p+3) I don't understand

4=0

Step-by-step explanation:

Simplifying

(-9p + 7) + - 1 (-9p + 3) = 0

Reorder the terms:

(7 + - 9p) + - 1 (-9p + 3) = 0

Remove parenthesis around (7 + - 9p)

7 + - 9p + - 1 (-9p + 3) = 0

Reorder the terms:

7 + - 9p + - 1 (3 + - 9p) = 0

7 + - 9p + (3 * - 1 + - 9p * - 1) = 0

7 + - 9p + (-3 + 9p) = 0

Reorder the terms:

7 + - 3 + - 9p + 9p = 0

Combine like terms: 7 + - 3 = 4

4 + - 9p + 9p = 0

Combine like terms: - 9p + 9p = 0

4 + 0 = 0

4 = 0

Solving

4 = 0