Question

How many gallons of a 20% salt solution must be mixed with 4 gallons of a 30% salt solution to make a 25% salt solution?

Answer 1

Answer:

4 gallons

Step-by-step explanation:

Say that g = the number of gallons of a 20% salt solution,

The first thing we want to do here is to convert each " percentage " into decimal form, to make things a bit simpler here.

( $20(percent) = 0.20$

( $30( percent ) = 0.30$

( $25( percent ) = 0.25$

Before this mixture takes place, the 20% salt solution is associated with g, the number of gallons of a 20% salt solution. Respectively the 30% salt solution is associated with 4 gallons. After mixing the two ( g and 4 ) the 25% salt solution should be associated with g + 4. We can therefore conclude the following equation -

0.20( g )+0.30( 4 ) = 0.25( g + 4 )

And now, let us solve for " g, "

0.2g + 1.2 = 0.25g + 1

- 0.2g       = - 0.2g

_________________

1.2 = 0.05g + 1

- 1  =          -  1

_________________

0.2 = 0.05g,

g = 4 gallons of a 20% salt solution