How do you solve for each one Right out all the steps please

How do you solve for each one? Right out all the steps please.

?0 = .7?0 +.5?1
?1 = .4?2 +.2?3
?2 = .3?0 +.5?1
?3 = .6?2 +.8?3

?0 + ?1 + ?2 + ?3 = 1

Solution

This question is impossible, or incorrectly written.

?0 + ?1 +?2 + ?3 = 1 is not possible

0 + 1 + 2 + 3 = 6

It doesn\'t matter what ? is, it cannot make the above statement true.