Answer:108 houses
Step-by-step explanation:
Step 1: ratio of flats to bungalows is 10:5 and the bungalows are 30, therefore:
(10*30)/5 = 60 flats
Step 2: the ratio of houses to flats is 9:5 and the number of flats is 60, therefore
9*60/5 = 108 houses
