[tex]6.75+\frac{3}{8}x=13\frac{1}{4}\\\\ 6\frac{3}{4}+\frac{3}{8}x=13\frac{1}{4}\\\\ \frac{3}{8}x=13\frac{1}{4}-6\frac{3}{4}\\\\ \frac{3}{8}x=12\frac{5}{4}-6\frac{3}{4}\\\\ \frac{3}{8}x=6\frac{2}{4}\\\\x=\frac{13}{2}\cdot\frac{8}{3}\\\\x=\frac{52}{3}\\\\ x=17\frac{1}{3}[/tex]
