In scientific notation, it would be 2x10^3.
An easy trick to help remember when it is a multiple of 10 is that you do the numbers that aren't zero (2) times 10 and the exponent is how ever many zeros there are after the other numbers (3).
Remark
Thank you for editing your question. Very few people do and those of answering don't really like reporting incomplete questions (or I don't).
You could write it like this.
Solve Multiply both sides by 7
x > 800 * 7
x > 5600 That would make the inequality equal to 800 if x = 5600.
You need to go just 1 step further. Try 5607. When you divide that by 7, you get 5607/7 = 801 which is 1 bigger than 800.
5607 <<<<< Answer
5 1/2 - u = 9/4 U= 13/4
Basically you have to get the variable (u) by itself. Doing this by doing the opposite of what it’s doing to both sides of the equation.