Answer:
9 + 10 +x= 21
x=21-19
x=2
add 2 in left hand side to get 21
Answer:
1.14 liters
Step-by-step explanation:
We have 8% glycerin solution and we need to make it 16% glycerin solution [more concentration].
When we add "x" liters, we add glycerin as well as changes the total. in 12 Liters, there is 12 * 0.08 = 0.96Liters of glycerin. How much we need to add to this??
Note, 16% = 0.16
We can write a Ratio as shown below, cross multiply and solve for x:

We need to add around 1.14 liters
4/7=28/(x+18)
4/7 =28/x+18
-18 | -18
|
__________
-17 2/7=28/x
*28 | *28
|
__________
-484 = x