PyQT5 - align left

[frohr]

Hi, I am stuck on very stupid thing.
I need align items left and width must be according text length and for line_edit fixed length.
Thank for any advice.

IMAGE

 self.label = QLabel("Low-pass (Hz): ", self)
        self.label.setFont(QFont('Arial', 10))
        self.label.setAlignment(Qt.AlignLeft)

        self.line_edit = QLineEdit("10", self)
        self.line_edit.setFont(QFont('Arial', 10))
        self.line_edit.setAlignment(Qt.AlignLeft)
        self.line_edit.setFixedWidth(120)
   
        self.label1 = QLabel("High-pass (Hz): ", self)
        self.label1.setFont(QFont('Arial', 10))
        self.label1.setAlignment(Qt.AlignLeft)
   
        self.line_edit1 = QLineEdit("10", self)
        self.line_edit1.setFont(QFont('Arial', 10))
        self.line_edit1.setAlignment(Qt.AlignLeft)
        self.line_edit1.setFixedWidth(120)
   
 
        self.combo_box = QComboBox(self)
        self.combo_box.setFont(QFont('Arial', 10))
         
        geek_list = ["Hanning", "Hamming", "Flat", "None"]
        self.combo_box.setEditable(False)
        self.combo_box.addItems(geek_list)
        self.combo_box.setFixedWidth(120)
        
        
        buttonbox3.addWidget(self.label)
        buttonbox3.addWidget(self.line_edit)
        buttonbox3.addWidget(self.label1)
        buttonbox3.addWidget(self.line_edit1)
        buttonbox3.addWidget(self.combo_box)