Help. i do not understand ​

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

Anew shopping mall is gaining in popularity. every day since it opened, the number of shoppers is 5% more than the number of shoppers the day before. the total number of shoppers over the first 10 days is 1258 how many shoppers were on the first day?

Credit card a offers an introductory apr of 3.4% for the first three months and standard apr of 15.7% thereafter,