Astrings is divided into three sections. the first section is three-fourths the length of the third section. the second sectionis one-half the length of the third section. if the length of the string is 18cm, what is the length of the first section?

Let's name the third section x
The first section is then 3/4 x
And the second one is 1/2 x

Together they are 18 cm long

Which means

And multiplied by 4 and devided by 9 this equals

So we have the third section's lenght.
But they are asking for the first one's. The first section is 3/4x




The lenght of the first section is 6cm