-7(3+5x)=399? I'm confused please help me!

Answer 1

- 7 ( 3 + 5 x ) = 399

- 7 * 3 - 7 * 5 x = 399

- 21 - 35 x = 399 Add 21 to both sides

- 21 - 35 x + 21 = 399 + 21

- 35 x = 420 Divide both sides by - 35

- 35 x / - 35 = 420 / - 35

x = - 12

Proof :

- 7 ( 3 + 5 x ) = 399

- 7 [ 3 + 5 * ( - 12 ) ] = 399

- 7 ( 3 - 60 ) = 399

- 7 * ( -57 ) = 399

399 = 399