Answer:
$9600 saving / year
Explanation:
1/5 of $21000 = 21000 / 5 = $4200 / month on rent
3/7 of $21000 = (21000 / 7) x 3 = $9000 / month on food (shocking right :) food is expensive)
1/3 of $21000 = 21000 / 3 = $7000 on other expenses / month
total savings/month = salary/month - rent/month - food/month - other expenses/month
total savings/month = 21000 - 4200 - 9000 - 7000
total savings/month = $800
BUT the question asks for savings per year. therefore, we must multiply the savings per month by total months per year (12)
800 x 12 = $9600
the person's total savings per year, with a salary of $21000 per month, is equal to $9600 per year