The multiplication property of equality says that if you multiply both sides of an equation by the same number, then the sides remain equal. Hence whatever is multiplied to one side of the equal sign must be multiplied to the other side. If a=b, then ac=bc.
For example, in order to solve the equation 5x=7, try to get x on its own by dividing 5x by five. Because you divided 5x by 5, you must do the same the other side of the equal sign. Then the answer will be x=7/5.
Another example is 2x=8. In order to solve the problem you must divide both sides of the equation by 2. Hence the answer is x=4.