Question 1205576
<br>
For new tutor CharcoalRobin....<br>
(1) Learn how to use html to make your posts readable.  Your post with the whole solution in a single paragraph is extremely hard to read.<br>
You can learn some of the basics by looking at the responses from other tutors and clicking on "show source".<br>
(2) Check you work and your answer before submitting your response.  We are all capable of making arithmetic errors....<br>
Here is an informal mental solution that solves the problem by the same path as the formal algebraic solution shown by tutor @ikleyn.<br>
Since there are twice as many of the candies at $1.80/kg as there are at $1.60/kg, make groups of 2kg at $1.80/kg and 1kg at $1.60/kg, costing a total of 2($1.80)+$1.60 = $5.20.<br>
Since the total cost is $20.80, the number of these groups is $20.80/$5.20 = 4.<br>
So there are 4*2 = 8kg of candies at $1.80/kg and 4kg at $1.60/kg.<br>
ANSWER: 8kg at $1.80/kg and 4kg at $1.60/kg<br>
CHECK: 8($1.80)+4($1.60) = $14.40+$6.40 = $20.80<br>