{"id":"roi-calculator","engine":"core","category":"math","name":"Rendimiento sobre el coste","fields":[{"key":"cost","label":"Coste","type":"number","default":5000,"required":true,"min":0.000001},{"key":"value","label":"Valor","type":"number","default":6500,"required":true},{"key":"fees","label":"Costes adicionales","type":"number","default":100,"required":true}],"sample":{"cost":5000,"value":6500,"fees":100}}