38
Solving word problems: price and cost
Textbook: Part 1, lesson 38, pp. 117–119
GoalSolve problems about profit and loss, letter expressions and time.
New words
profit · foydaloss · zararnet profit · sof foydaletter expression · harfiy ifoda
Explanation
If income is greater than expenses, there is a profit: profit = income − expense. If expenses are greater than income, there is a loss: loss = expense − income. Net profit is the profit minus extra costs (fares, rent). We write an unknown amount as a letter and then put numbers into the expression.
Worked examples
A farmer buys potatoes at 4 800 so‘m and sells them at 6 500. The profit is 1 700 so‘m per kg, 102 000 so‘m on 60 kg. With 25 000 for fares and 30 000 for rent the net profit is 47 000 so‘m.
If 410 000 so‘m was earned in October and 450 000 spent, the loss is 40 000 so‘m.
Class activity
“Profit or loss?”: children get cards showing different incomes and expenses. They say “profit” or “loss” and work out the difference.
Practice
1
Potatoes bought at 4 800 so‘m/kg are sold at 6 500. If 60 kg are sold and fares cost 25 000 and rent 30 000 so‘m, what is the net profit?
47000
2
In October 410 000 so‘m was earned and 450 000 spent. Was there a profit or a loss? How much?
A loss of 40 000 so‘m
3
One pen costs 3 400 so‘m. n pens cost n × 3 400 so‘m. What is the cost if n = 45?
153000
4
Laylo earns m so‘m on each working day and n so‘m on each rest day. A week has 5 working days and 2 rest days. If m = 6 000 and n = 9 000, how much does she earn in a week?
48000
5
A shop is open 8:00–13:00 and 14:00–19:00. How many hours a day is it open?
10