Lay volume In play. Help please

In my trigger in play i want back a horse if the sum of the amount of money waiting in the 3 best lays price are greater than 200. There is a expresion for do that.¿¿??

Example my trigger its going to back a horse in play at 1.50 but before that i want the trigger check the condition at  the 3 best lay price offer for example( 1.53,1.55 and 1.60)  the aumont waiting in that odds are greater than 200 .

Thanks 

i put and selections Trigger expresion r_1_lay_amount is greater than 200 but not sure if thats its correct. I think that check the 3 best aviable prices, but if i only want check the amount on the best price¿? thanks for everything

Hi
It is lay_volume for the sum of the best three lay prices. The setting for retrieve all price offers must be switched OFF.

OR

you can use lay_amount+lay_amount2+lay_amount3

otherwise for the best lay price you are correct, it is lay_amount

thanks a lot