Answer :

[tex]7\%=\frac{7}{100}=0.07\\\\x-the\ number\\\\0.07x=6.3\ \ \ \ \ |divide\ both\ sides\ by\ 0.07\\\\x=\frac{6.3}{0.07}\\\\x=\frac{630}{7}\\\\\boxed{x=90}\leftarrow answer[/tex]