By assuming the last character either "x" or number, the arraf formula
is:

Condition1 ("x" as the last character):

=SUM(IF(RIGHT($E$4:$E$56,1)="x",$G$4:$G$56))

Condition1 (there is no "x" at the end):

=SUM(IF(RIGHT($E$4:$E$56,1)<"x",$G$4:$G$56))

Don't forget to press CTRL + SHIFT + ENTER after editing the formula.