This is the commutative property of multiplication. Commutative property has to do with order. Whereas the equation begins with 5+ac, its equivalent reads 5+ca. The order of the variables has changed.
reiprocal property is also known as the commutiave property which staes ab=ba so we have 5+ac=5+ca we can ignore the 5 since it was no changed ac=ca very close to ab=ba aka commutative property
