Deep-inelastic inclusive electron-scattering cross sections from 40 Ca, 48 Ca, and 56 Fe have been measured at 60°, 90°, and 140° and at energy transfers including the A(3,3) region. The transverse response function in the momentum interval 300 MeV/c < |q| < 600 MeV/c was extracted by the Rosenbluth prescription. Different theoretical approaches to the quasielastic region are compared to the data. A mass-number scaling is observed.PACS numbers: 25.30.Fj At energies above giant resonances, the inelastic electron-scattering cross section can be divided into three regions. First, there is the quasielastic region which appears as a broad peak, in which the dominant process is direct ejection of one bound nucleon from the nucleus through elastic scattering. Second, as the energy transfer becomes larger than the pion mass, it becomes possible to produce real pions and the A (3,3) resonance gives rise to a second large and broad peak. Finally, between these two peaks there iswhere R L and R T are the longitudinal and transverse response functions,