the salesperson earns a fixed cost of $ 30 plus 2/9th of his sales
we have to find how many sales he gets to earn $ 100 for one day
so lets say that the number of sales for the day - x sales
and he earns 2/9th of his sales
therefore amount he earns for x sales is - 
this value plus his fixed earnings of $ 30 per day
so the amount he earns is 2x/9 + 30
this equals $ 100
so we can write the following equation



2x = 70 * 9
2x = 630
x = 315
so the amount of sales he earns for that day is 315 sales
He needs to work 22 hours :)
We know that
case 1) -10/-7-----> 10/7-------> is not <span>equivalent to -10/7
case 2) </span>-3 1/7----> (-3*7+1)/7----> -20/7 ------> is not equivalent to -10/7
case 3) 1 3/7-----> (1*7+3)/7----> 10/7 ------> is not equivalent to -10/7
case 4) - -10/-7---> +10/-7----> -10/7------> is equivalent to -10/7
case 5) -1 3/7----> (-1*7+3)/7----> -4/7 ------> is not equivalent to -10/7
the answer is
- -10/-7