First you need to find a expression that gives you any number of sticks for a number(n) of houses. Start by looking at one house, then two and the third. You will see that the number of sticks is found by 4n + 1, and n is the number of houses.
So to find how many houses there will be if 61 sticks are used, you set 61 equal to the expression 4n + 1 and you should get n = 15
