Using Query List Action how can I do calculations on another field in the same list

Hi,

 I am new to Nintex Workflows.

The scenario that I am facing is as follows:

There is a first List named TestingList.

There is a second List named RateList.

The TestingList contains various fields, among them which are important: Cost1, Cost2, AcCost1, AcCost2.

The RateList has fields: Title, Rate.

The RateList has following entries:

Name1,5

Name2,10

The Calculations are:

AcCost1=AcCost1+(Cost1*Rate) [In this example, Rate is directly proportional to Rate field in RateList. i.e Rate=5]

AcCost2=AcCost2+(Cost2*Rate) [In this example, Rate is directly proportional to Rate field in RateList. i.e Rate=10]

Using Query List action how can I do this?

 Thank You