Is the banking transaction in which the bank pays 70% of the value of the equipment and the client pays 30%, and then the client repays the amount through a monthly deduction from the salary for a period of 3 years with a 9% increase to the bank, permissible or impermissible?

If the bank genuinely purchases the commodity and then sells it on installments—even at a higher price—this is a Murabaha sale, which is Islamically permissible and practiced by Islamic banks. However, if the bank does not actually purchase the commodity, but rather pays money on your behalf for you to repay with interest, then this transaction is forbidden; because it is a loan with a benefit, and that is usury (riba), and this is what conventional (ribawi) banks do.