Why was an attack against vicksburg by river just not possible for union forces?

What is the value of the expression below? 148+(-6)| + |– 35= 7|

Thomas is using a drawing program to complete a construction. which construction could he be completing? two perpendicular lines are drawn. inscribing an equilateral triangle in a circle inscribing a square in a circle inscribing a regular pentagon in a circle inscribing a regular hexagon in a circle

Without any equipment, you can see stars that are 2{,}800{,}0002,800,0002, comma, 800, comma, 000 light-years away. by looking through a small telescope, you can see stars that are 3{,}112{,}000{,}0003,112,000,0003, comma, 112, comma, 000, comma, 000 light-years away. approximately how many times as far can you see using a small telescope as without any equipment?