For the house A we have:
f (x) = 124270 (1.04) ^ x
Evaluating for 7, 8, 9 and 10 we have:
f (7) = 124270 (1.04) ^ 7 = 163530.8422
f (8) = 124270 (1.04) ^ 8 = 170072.0759
f (9) = 124270 (1.04) ^ 9 = 176874.9589
f (10) = 124270 (1.04) ^ 10 = 183949.9573
For house B we have:
f (x) = 114270 (1.05) ^ x
Evaluating for 7, 8, 9 and 10 we have:
f (7) = 114270 (1.05) ^ 7 = 160789.3653
f (8) = 114270 (1.05) ^ 8 = 168828.8336
f (9) = 114270 (1.05) ^ 9 = 177270.2752
f (10) = 114270 (1.05) ^ 10 = 186133.789
We observe that for years 7 and 8 the value of house A is greater than the value of house B.
Answer:
7 and 8
10 = ax - 3b
First, add 3b to both sides. / Your problem should look like: 10 + 3b = ax.
Second, divide both sides by a. / Your problem should look like:

= x.
Third, switch sides. / Your problem should look like: x =

which is your answer.
Width of the actual barrier = 1.2 miles
Width of the barrier in the blueprint = 2 inches
2 inch dimension of blueprint = 1.2 miles of original
So, 1 inch dimension of blueprint = 1.2/2 = 0.6 miles.
Since the length of the barrier in the blueprint = 9 inches,
length of the actual barrier = 9(0.6) = 5.4 miles.