Answer:
Step-by-step explanation:
[tex]\frac{1}{x}+\frac{1}{3x}=5\\\\\frac{1*3}{x*3}+\frac{1}{3x}=5\\\\\frac{3}{3x}+\frac{1}{3x}=5\\\\\frac{4}{3x}=5\\\\4=5*3x\\\\4=15x\\\\\frac{4}{15}=x[/tex]
x = 4/15
[tex]\frac{3}{4}x=\frac{3}{4}*\frac{4}{15}\\\\=\frac{1}{5}[/tex]