Answer :
S=sweaters, ST=shirts, SL=slacks.
Add 4S and 6ST and that should add up to 10 in total, then times 10S/ST by 3SL to get 30 as a grand total.
Add 4S and 6ST and that should add up to 10 in total, then times 10S/ST by 3SL to get 30 as a grand total.