Answer:
-0.7
Step-by-step explanation:

You can choose any digits you wish for
and
but the difference must be 0.7. I chose 1.0 and 0.3.

3+x/2=10
subtract 3 from both sides
x/2=7
divide each side by 2
x=3.5
make sure to check the work
Answer:
28 l of 80%
42 l of 30%
Step-by-step explanation:
Target is 70 l of 50% solution
It will contain 70*0.5= 35 l of alcohol
x l of 80% solution and y l of 30% solution mixed to get the target solution
x+y=70 is the equation for total volume, and
0.8x+0.3y= 35 is the equation for the alcohol content. Solving this:
- y= 70-x
- 0.8x+0.3*(70-x) = 35
- 0.8x+21- 0.3x= 35
- 0.5x= 35-21
- 0.5 x= 14
- x= 14/0.5
- x=28 l of 80% solution
then
- y= 70-x= 70 -28 l= 42 l of 30% solution
What an awesome question!