Recovering a missing value from a graph or table

The line graph shows the number of visitors to a museum in each year from twenty twenty-one to twenty twenty-four. The point for twenty twenty-four is hidden and marked with a question mark. The increase in the number of visitors from twenty twenty-three to twenty twenty-four was 3 times the increase from twenty twenty-two to twenty twenty-three. How many visitors were there in twenty twenty-four? Try it first. Pause if you like. The question triples an increase. Which two printed readings give that increase? The large grid steps are five hundred visitors. Each dashed line halfway between them adds two hundred and fifty. Follow the twenty twenty-two point across. It is halfway between one thousand and one thousand five hundred: one thousand two hundred and fifty visitors. The twenty twenty-three point is at one thousand five hundred visitors. From the graph, there were one thousand visitors in twenty twenty-one, one thousand two hundred and fifty in twenty twenty-two, and one thousand five hundred in twenty twenty-three. Subtract the twenty twenty-two reading from the twenty twenty-three reading, in columns. Ones: 0 minus 0 is 0. 5 hundreds become 4; the tens become 10. Tens: 10 minus 5 is 5. Hundreds: 4 minus 2 is 2. Thousands: 1 minus 1 is 0, so no thousands are left. Increase from twenty twenty-two to twenty twenty-three equals one thousand five hundred minus one thousand two hundred and fifty, which is two hundred and fifty. Two hundred and fifty is the increase. This is the amount we multiply by 3. Increase from twenty twenty-three to twenty twenty-four equals 3 times two hundred and fifty, which is seven hundred and fifty. The new rise is seven hundred and fifty. Which printed value must it be added to? Add the rise to the twenty twenty-three reading, in columns. Ones: 0 plus 0 is 0. Tens: 0 plus 5 is 5. Hundreds: 5 plus 7 is 12. Rename 12 hundreds as 1 thousand and 2 hundreds. Thousands: 1 plus 1 is 2. Visitors in twenty twenty-four equal one thousand five hundred plus seven hundred and fifty, which is two thousand two hundred and fifty. Plot the open point at two thousand two hundred and fifty, on the dashed line. Then join it to the previous point. There were two thousand two hundred and fifty visitors. Find the earlier increase, multiply that increase, then add it to the last known reading.

The table shows the number of packets of chicken rice a stall sold on each of four days. It sold 86 packets on Thursday, one hundred and thirty-two on Saturday and one hundred and eighteen on Sunday. The cell for Friday is marked with a question mark. The stall sold 60 more packets on Friday than on Thursday. Each packet cost 5 dollars. How much did the stall collect from the packets sold on Friday and Saturday altogether? Try it first. Pause if you like. Which count must be found before we can work out the money collected? Thursday has 86 packets. Friday has 60 more than Thursday. Friday equals 86 plus 60, which is one hundred and forty-six packets. Fill Friday with that count. The question asks for Friday and Saturday. Those are the two days to add. Friday and Saturday equal one hundred and forty-six plus one hundred and thirty-two, which is two hundred and seventy-eight packets. Amount collected equals two hundred and seventy-eight times 5, which is one thousand three hundred and ninety dollars. Find the missing count first. Then use it to answer the question.