What do you have?
 

1st and 10 for A on A’s 40 yard line A1 runs to the 50, where his Facemask gets pulled and twisted, he fumbles and A2 picks up ball and runs to B20 and fumbles. B2 picks the ball up and returns the ball to B’s 35, during the return there is a hold by A3 at B’s 30 yard line. What do you have?

B should be able to keep the ball if it declines the holding by A penalty but will have the facemask penalty accessed, so it should be 1st and 10 for B from the 15 yard line Correct?

Since B fouled before gaining team possession they may not keep the ball.

Fouls by both teams...offset, repeat.

B must gain possession with "clean hands" to keep the ball.

Always remember the "clean hands" principle. B can not retain possession if they commit the first foul and then obtain possession.