Question 5762
Let x represent the amount of the $1,20 coffee. Then 30-x represents the amount of the $0,93 coffee
Use the following guideline:
Amount of coffee worth $1,20 + Amount of coffee worth $0,93 = Total worth $1,02
       1,20(x)               +              0,93(30-x)      =   1,02(30)
Now let'ss simplify the terms:
1,2x + 27,9 - 0,93x = 30,6 Combine like terms
0,27x +27,9 = 30,6 Substract 27,9 from both sides
0,27x +27,9 - 27,9 = 30,6- 27,9
0,27x = 2,7 Divide both sides by 0,27
0,27x/0,27 = 2,7/0,27
x = 10
Therefor: 30-x = 30-10 = 20
Check:
1,2(10)+0,93(30-10)= 1,02(30)
12     +18,6       = 30,6
30,6 = 30,6
So, 10 pounds of half bean coffee worth $1,20 per pound are mixed with 20 pounds of whole bean coffee worth $0,93 per pound.
You can use this guideline not only for mixture problems of this type(amount + price) but also for problems with amount and percent.
Hope this helps