“Estimating the Amount of Defective Vaccines and Their Impact on the Environment Using A System of Simultaneous Equation”. 2024. Journal of Al-Rafidain University College For Sciences ( Print ISSN: 1681-6870 ,Online ISSN: 2790-2293 ) 54 (1): 292-302. https://doi.org/10.55562/jrucs.v54i1.599.