Joan owns a lawn maintenance company, and Sally owns a machine repair shop. For the month of July, the following transactions occurred:

July $3$ Joan provides lawn services to Sally$$s repair shop on account, $$300.$

July $6$ One of Joan$$s mowers malfunctions. Sally provides repair services to Joan on account, $$250.$

July $9$ Sally pays $$300$ to Joan for lawn services provided on July $3.$

July $14$ Sally borrows $$400$ from Joan by signing a note.