Check whether the ratio forms a proportion 

$\frac{7}{8} and 14:16$

Find the value of $x$

$x:4 = 6:8$

Find the value of $x$

$14:x = 7:9$

Find the value of $x$

$4:6 = x:18$

Find the value of $x$

$8:10 = x:25$

Find the value of $x$

$5:15 = 4:x$

Find the value of $x$

$16:24=6:x$

Find the value of $x$ so that the given four numbers are in proportion 

$x,6,10 and 15$

Find the value of $x$ so that the given four numbers are in proportion 

$x,4,15 and 30$