         guard
             
             let project:DProject = self.project,
-            var equations:[DEquation] = project.equations?.array as? [DEquation]
+            let equations:[DEquation] = project.equations?.array as? [DEquation]
         
         else
         {

                        polynomialA:polynomial,
                        polynomialB:result)
                    
                    result.coefficientDividend = kDefaultDividend
                    result.coefficientDivisor = kDefaultDivisor
                    result.isPositive = kDefaultPositive
                    result.showAsDivision = kDefaultDivision
                    result.indeterminate = nil
                }
            }
            else
            {
                DManager.sharedInstance?.delete(object:equation)
                
                //needs to remove equation from array
            }
        }
        

        {
            guard
            
                let polynomials:[DPolynomial] = equation.polynomials?.array as? [DPolynomial],
                let result:DPolynomial = equation.result
            
            else
