A classical model for substantiating decisions has as input data the matrix of the results obtained for each criterion and each decision variant. Often, the values of the results are uncertain because they are expressed by statements such as "the value is around b, certainly it is not less than a and does not exceeds c", (alesblesc), which is mathematically modelled by triangular fuzzy numbers v tilde = (a, b, c). The article defines the basic operations (addition, substraction, multiplication and division) with this type of fuzzy numbers as well as an order relation. All these allow fuzzy models to be resolved by applying the method of global utilities and the ELECTRE method. They were applied to a hipothetical fuzzy model of small dimensions.