Variable cost, semi-fixed cost, deferred variable cost, curve variable cost. Incremental mixed cost is a kind of capital investment in the education process, which is mainly divided into four cost types: variable cost, semi-fixed cost, deferred variable cost and curve variable cost. Cost is the value category of commodity economy and an integral part of commodity value. If people want to carry out production and business activities or achieve certain goals, they must spend certain resources, and the monetary expression and objectification of the resources spent is called cost.