Here's the equation for one year:
0.03(8000) + 8000
For four years:
4(0.03(8000)) + 8000
0.12(8000) + 8000
To make it simpler/smaller:
1.12(8000) = 8960
You can make 960 more dollars, and you now have $8960
The drawing shows a circle, with the two lines forming a cross assumed to be perpendicular to each other, so this is most likely to be a square, as the four points at which the perpendicular lines intersect with the circle can be connected to form a square.
We would need 3 points for an equilateral triangle, 5 for a pentagon, and 6 for a hexagon, which do not fit the current steps.
He needs 6 more hot dog buns. You just simply subtract 12 from 18.