x1 is the x2th-order time-differintegral of the cost/fee/debt or revenue ((possibly: monetary) charge/value) of or at which x3 is sold to/bought by customer x4 from vendor/seller x5, with differintegral starting point x6.
If x2 = -1, then this word references the cost or revenue per unit time/hourly rate of monetary charge of the sale/purchase. If x2 = -2, then this word references the rate of change, with respect to time, at which that hourly charge rate is itself changing (such as due to inflation or adjustments therefor). The reward/cost need not be strictly monetary; barter is an exchange of goods in kind, for example; food-gathering measures reward in terms of extractable energy-density from the gathered food. "salri" is an experimental gismu.