A is the same as dividing a number by 10
(x-12)(x-12) would factor to x²-24x+144.
(x-12)(x+12) = x²+144
Option C is correct :)
notice above... we use the decimal format for the percentage, thus 20% is really just 20/100, 40% is 40/100 and so on.
so.. whatever "x" and "y" amounts are, we know they have to add up to 60 Liters, that is x+y = 60
and whatever the concentration amount of each is, it must add up to (60)(0.40), that is 0.20x+0.50y=(60)(0.40)
thus
solve for "x", to see how much of the 20% solution will be needed
what about "y"? well, y = 60 - x
It gets 25$ off at first then 30$ off so the price would be 70$
The answer would be 1.
This is due to 5+8 equaling 13.
Then if you subtract 1 from 14 you also get 13.