The number line shows the midday temperature recorded at two weather stations in Scotland.
Station A, near the summit of Ben Nevis, is at -12 degrees C.
Station B, in the valley below, is at 9 degrees C.
Work out the difference between the temperature at Station B and the temperature at Station A.
Figure (to be drawn): A horizontal number line from -20 to 20, marked in intervals of 5. An arrow points to -12, labelled Station A. A second arrow points to 9, labelled Station B.
(Total for Question 11 is 2 marks)