Answer: 
Island A=17 house 
Island B= 13 house 
Island C=23 house 
Explanation:
Island AB=30 house 
Island AC=40 house 
Island BC=36 house 
Island ABC=53 house 
53 - 30= 23 house which is the total of house on island c
53-40=13 house which is the Total of house on island b
53-36=17 house which is the Total of house on island A