You must make a
proportion.
92% is part of 100%
540 would need to be the 92% of the plant bought. That means 540 is the part and the whole would be the unknown (let's make this x)
Set up your proportion like so...

Cross multiply...
92x = 540 * 100
92x = 54000
Isolate x by dividing 92 to both sides...
92x/92 = 54000/92
x = 586.9565
Since you can't buy a decimal of a plant you will have to round this number up to the next whole number...
587
To have 540 of the plants arrive alive the nursery owner must order 587 plants
Hope this helped!
~Just a girl in love with Shawn Mendes