Answer:
u = 1/2
Step-by-step explanation:
[tex]\frac{3}{4} u + \frac{1}{2} =\frac{7}{8} \\\frac{3}{4} u =\frac{7}{8} - \frac{1}{2} \\\frac{3}{4} u =\frac{7}{8} - \frac{4}{8}\\\frac{3}{4} u =\frac{3}{8} \\u =\frac{3}{8}/\frac{3}{4} \\u =\frac{3}{8}*\frac{4}{3} \\u =\frac{12}{24} \\u =\frac{1}{2} \\[/tex]
