This is simply a question about ratios. This ratio means that for every 1 cm on the map, there are 12 km in actuality. You can set this problem up in fractions:
1 cm 12 cm
-------- = ----------
12 km x
To solve for x, we cross-multiply, for the moment ignoring units. Remember, your answer will be in km.
1*x=12*12
x=144
If x=144, then for 12 cm, there are 144 km.
The first term a = 1,
Common difference, d: 7 - 1 = 6.
a(n) = a + (n -1)d,
For 30th term. = 1 + (30 -1)*6
= 1 + 29*6 = 1 + 174 = 175
Keeping in mind that 29/6 is greater than 4, is actually 4 and 5/6, so the amount we'll "add" will be a negative one.
Answer:
$20,720
Step-by-step explanation:
$518,000 x 4% = $20,720