First what you want to to do it set up an inequalty. 80% as a fraction is 80/100. You would set that equal to a fraction where x is the number in place of 80% over 1400.
\(\\ \frac{80}{100} = \frac{x}{1400} \)
After this step cross multiply and you get...
\((80)(1400)=100x\)
Solve for x and you will get the answer, which is:
\(x = 1120\)