Question

.

Answer 1

Answer:

3 gallons

Step-by-step explanation:

Let

x ----> the amount of pure acid (100% solution) in gallons

Remember that

$100\%=100/100=1$

$20\%=20/100=0.20$

$60\%=60/100=0.60$

we know that

$(1)(x)+(0.20)(3)=(0.60)(x+3)$

solve for x

$x+0.60=0.60x+1.80$

$x-0.60x=1.80-0.60\\0.40x=1.20\\x=3\ gal$

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