I have an Eco doubt, please please help

[Albus Dumbledore]

Hey,
I'm solving eco w11/32
http://www.xtremepapers.com/papers/CIE/Cambridge%20IGCSE/Economics%20(0455)/0455_w11_qp_32.pdf
And I cannot understand q2 b(i).

Here is the extract for it, the Philippenes one: http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Economics (0455)/0455_w11_in_32.pdf

And this is the mark scheme: http://www.xtremepapers.com/papers/CIE/Cambridge IGCSE/Economics (0455)/0455_w11_ms_32.pdf