Answer:
3 gallons
Step-by-step explanation:
Let
x ----> the amount of pure acid (100% solution) in gallons
Remember that



we know that

solve for x


therefore
3 gallons of pure acid should be mixed with 3 gallons of a 20% acid solution in order to get a 60% acid solution
Id say the first one because the points just touch down
i speak Russian but can’t understand this very well, the instructions aren’t really clear, what’s the translation?
The ONLY multiple of 11 that's between 70 and 80 is 77 .