Prove that the centre of mass of two particles divides the line joining the particles in the inverse ratio of their masses?

can someone help~

Kelly is a salesperson at a shoe store, where she must sell a pre-set number of pairs of shoes each month. at the end of each work day the number of pairs of shoes that she has left to sell that month is given by the equation s=300-15x , where s is the number of pair of shoes kelly still needs to sell and x is the number of days she has worked that month. what is the meaning of the number 300 in this equation

In an improper fraction, is the numerator equal to, less than, or greater than the denominator

If i had 1234 apples and 1 banana what is the total amount