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?

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.

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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

yes

step-by-step explanation:

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this