Ok first you want to reduce down to get the poly into its smallest form. You can do this by dividing by 10 which leaves you with a^2-4a+3. Now you use regular factoring rules. For this equation you need what multiplies to get +3 and adds to get -4. Which is a -1 and a -3. Now you put it into the blanks to get 10(a-1)(a-3)
