Answer:
Step-by-step explanation:
Let, the three islands A, B and C has a, b and c houses respectively.
According to the question, a + b = 15; a + c = 17; b + c = 12; a + b + c = 22.
Adding [ a + b = 15; a + c = 17]-these two, we get, [tex]a + (a + b + c) = 15 + 17 = 32\\a + 22 = 32\\a = 10[/tex].
Now, [tex]a + b = 15\\10 + b = 15\\b = 5[/tex].
[tex]a + c = 17\\10 + c = 17\\c = 7[/tex].