assuming that they each work 24hrs a day 7 days a week (I haven't got anything else to go on...sorry) to find the total for Joshua you must first multiply 13x24 = 312, for the toys sold per day, and then 312x7 = 2184, for the number of days per week. so j = 2184
then for Sarah's total we must first multiply 16x24 = 384 for the toys sold per day and then 384x7 = 2688 for the toys sold per week. and 2688+20 = 2708 for the extra 20 she sold. so s = 2708
REMEMBER, THIS IS ASSUMING THEY WORK 24/7 MEANING THEY WORK 168 HOURS PER WEEK.
IF YOU NEED A DIFFERENT ANSWER LET ME KNOW AND I'LL TRY TO FIX IT. IF YOU LET ME KNOW THE HOURS THEY WORKED I CAN DO TAT FOR YOU AS WELL.