Gravar-mail: New Results on the SSIE with an Operator of the form <i>F</i>_Δ ⊂ <i>Ɛ</i> + <inline-formula><math display="inline"><semantics><mrow><msubsup><mi>F</mi><mi>x</mi><mo>′</mo></msubsup></mrow></semantics></math></inline-formula> Involving the Spaces of Strongly Summable and Convergent Sequences Using the Cesàro Method