Answer:
a)The total amount of her weekly stock sales = $7,200
b) The total amount of her yearly stock sales = $350,000
Step-by-step explanation:
(a) Let us assume that the total a mount of her sales in a week = $m
Commission earned in a week = $288
Now, 4 % of her total sales = $288
or, 4% of ($m) = $288
⇒
or, 
⇒ m = $7,200
Hence, the total amount of her weekly stock sales = $7,200
b) Let us assume that the total amount of her sales in a year = $k
The total amount of commission earned = $14,000
Now, 4 % of her total sales = $14,000
or, 4% of ($k) = $14,000
⇒
or, 
⇒ k = $350,000
Hence, the total amount of her yearly stock sales = $350,000