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Activity 58
Answer the following questions:
(a) If you had £3 in your bank account and drew out £10, how much would you have left?
(b) The temperature was −5 °C on Monday and dropped overnight by 6 °C. What was the temperature on Tuesday morning?
Answer
(a) 3 − 10 = −7,
so you would have −£7 left, i.e. you would have a £7 overdraft.
(b) −5 − 6 = −11,
so the temperature was −11 °C.
Activity 59
Evaluate each of the following:
(a) −3 + −12
(b) −4 − −11
Think of a financial context where each might be an appropriate calculation (bear in mind that negative numbers can represent debts).
Answer
(a) −3 + −12 = −15 (a debt of £3 plus a debt of £12 gives a debt of £15).
(b) −4 − −11 = −4 + 11 = 7 (incurring a debt of £4 and being let off a debt of £11 results in being £7 better off).
Activity 60
Kim was walking in Israel. She started at 37 metres below sea level and ended up at 42 metres above sea level. How far had she climbed up?
Answer
Kim started at −37 m and ended at 42 m. You want 42 − −37 = 42 + 37 = 79. So Kim climbed 79 m.