There are 155 Grade 12 students at Westdale High. The numberof students enrolled in the following courses is shown.

78 in biology

20 in biology and chemistry

70 in chemistry

10 in chemistry and physics

40 in physics

10 in biology and physics

2 in all three sciences

(a)Complete the Venn diagram to illustrate the situation. [1 mark]

(b)How many students do not take any of the three science courses? Explain clearly how you obtain this answer. [2 marks]