The ratio is 3:5.
[tex]\frac{x}{y}=\frac{3}{5} \ \ \ |\hbox{cross multiply} \\
5x=3y \ \ \ |\div 5 \\
x=\frac{3}{5}y[/tex]
You have to divide 72, so the sum of x and y is 72.
[tex]x+y=72 \ \ \ |-y \\
x=72-y[/tex]
Set both expressions equal to each other:
[tex]x=x \\
\frac{3}{5}y=72-y \ \ \ |\times 5 \\
3y=360-5y \ \ \ |+5y \\
8y=360 \ \ \ |\div 8 \\
y=45 \\ \\
x=72-y=72-45=27[/tex]
72 divided in a ratio of 3:5 is 27:45.
