A percent is just a fraction.
So take your two numbers and make a fraction with them ... 18/30 .
18 is 18/30 of 30 .
Now, to find the percent that's equivalent to 18/30 ,
first do the division:
18/30 = 0.6 .
Now, to change a decimal into percent,
move the decimal point two places that way ==> .
0.6 = 60% .
18 is 60% of 30 .