Plz ! what are some grammar rules for -er verbs?

Fill in the blank with the words in word bank

Mary just sent out invitations to her wedding last week the invitations were so heavy that she put more than just one stamp on each envelope she used 255 stamps and mailed out 85 invitations and see you as an equal amount of stamps on each envelope

Based on the audio, ¿qué día tiene pedro la clase de francés? a. el lunes b. el viernes c. el martes d. el jueves