I would take 50% of each of the prices because it is mixed equally. So, half of $8.50 is $4.25 and half of $6 is $3. add $4.25 and $3 to get $7.25 for the price of one pound of mix.
Find a common denominator.
we'll pick 12 so...
1/4 = 3/12
1/3 = 4/12
So you gave your sisters
3/12 + 4/12 = 7/12
You keep 12/12 - 7/12 = 5/12
11x-2; SInce you have to add 6x and 5x because they are 'like terms' meaning they share the same variable. You also add the 6 and the -8, which is basically doing 6-8, which equals -2. So, you put these two numbers together to get an expression of 11x-2.
Use the fraction addition formula.
Substitute the numbers into the formula.
a=5, b=1, c=1, d=7