how can constraints be used to model a real-world situation?

Which of the following is the sum of 3 1/6 + 6 3/8?

If you eat 4 medium strawberries, you get 48% of your daily recommenced amount of vitamin c. what fraction of your daily amount of vitamin c do you still need?

Harry owes the bank money. to repay his debt, he paid $150 back to the bank each month. after 10 months, his remaining debt was $6900. what was the original amount of harry's debt? how long did it take harry to pay back his entire debt?