Since ur using r as a variable the answer is r = 7.
she should add 7 liters of 10% acid solution
Explanation
Step 1
set the equation:
a) let X represents the amount os solution that is 4% acid
let Y represents the amount os solution that is 10% acid
so
I)

if he has 14 liters of 4% acid solution


Step 2
solve the equation :

therefore,
she should add 7 liters of 10% acid solution
I hope this helps you
There is a cube, a rectangle, and a trapezoid
Answer:
the answer is: 
Step-by-step explanation:
We get the answer using Pitagoras.

so
