Using inverse operations is helpful when solving equations. What is the inverse operation of division

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

Hormones perform important functions within the reproductive system. during puberty, a number of changes occur in the body. which hormone is responsible for the development of these characteristics in the female? estrogen progestin progesterone testosterone

Which is the value of this expression when p=3 and q=-9