Fewer because October clearly is higher then where December will be when the time comes.
So... the radiator has 15 liters of 70% antifreeze.. but needs an 80% antifreeze
well, so, you need to drain some and put some with higher percentage, seems to be, you will end up at the same 15 liters, possible the radiator's capacity, of 80% antifreeze
so, the same amount going out, of 70% is the same amount going in, of 100% antifreeze
now.. let's use the decimal format for the percents, or 70% is 70/100 or 0.7 and so on

so.. let's subtract, from the current solution, 0.7x and add 1x or x, our antifreeze concentration amount, should be 12 though
10.5 - 0.7x + x = 12
solve for "x"
You would pay 80% of the original price because 1/5 is 20% and you would subtract 20 from 100 to get 80 as your answer
Hope this Helps :3
Answer: 720
Step-by-step explanation:do 120 plus 120 plus 120 plus 120 plus 120 plus 120