10D + 5.50
$10 each, entire order is $5.50
use D as missing variable
$10D + $5.50 = Frank's DVDs
this is because the four is four hours and the n represents the 1 extra hour over the weekend.
b= i'm srry i don't know that one.
4+n=5 n=1 because if vernon plays 5 hours a week then 4+1=5 hours.
hope this : )
47 - 90 = 43
43 - 180 = x
x = 137