Question 1173323
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If a formal algebraic solution is not required, here is a quick and easy way to solve the problem with a bit of mental arithmetic.<br>
The prices per kg of the two ingredients are P140 and 280; the price per kg of the mixture is P180.<br>
180 is 40/140 = 4/14 = 2/7 of the way from 140 to 280 (look at the three numbers on a number line, if it helps).<br>
That means 2/7 of the mixture is the more expensive ingredient and 5/7 of the mixture is the less expensive.<br>
So the amount of soil supplement that must be added is (2/7)/(5/7) = 2/5 of the amount of aluminum nitrate.<br>
ANSWER: (2/5)(20) = 8kg = 8000g<br>
CHECK:
(20)(140)+8(280) = 2800+2240 = 5040
28(180) = 5040<br>