For these kinds of problems you just multiply the two numbers so 15(3)=45
there are 45 choices possible
The answer is k= m-9+8j over +9 (the third option)
For this there is a dotted line going through -2 on the graph and the shading is on the right side of the grid so -2,-1, and every positive number.
30×30=900
900/112.5=8 cameras to cover
112.5×4=450
900-450=450 ft left uncovered