ABCD ~ EFGH find value of y

How do i do this? i don’t understand

Tabby sells clothing at a retail store, and she earns a commission of 6.25% on all items she sells. last week she sold a pair of jeans for $32.50, a skirt for $18.95, and 2 blouses for $14.95 each. what was tabby's total commission? a $4.15 b $5.08 c $81.35 d $348.60

If private savings 'v' = 0.75s and total savings 's' equals $4.20 billion, solve for public and private savings.