Can someone please explain the geom notes to me? I am confused and my teacher told us to basically figure them out by ourselves so ya. Thanks! and please soon because I have a quiz!

What number should be added to both sides of the equation to complete this square? x^2-10x=7

Due to financial difficulties the owner of 4 skateboard stores is going to close 2 of his stores. based on the money earned at each store, which two stores should remain open?

Two trains leave a station on different tracks. the tracks make an angle of 130°, with the station as a vertex. the first train travels 100 km and makes its first stop at point a, while the second train travels 200 km and makes it first stop at point b. how far apart are the trains when both are at their first stop? round the answer to the nearest integer. a) 65 km b) 139 km c) 224 km d) 275 km