Hello, a69356!
When I first learned "Mixture Problems", I made a chart . . .A mixture of 125 galllons of wine and water contains 20% water.
How much water must be added to increase the percentage of the water to 25%?
The chart has the formula across the top:
. .
. .
We start with 125 gallons of mixture which is 20% water.
. . We have: . gallons of water.
Write this in the first row:
. .
We add gallons of water (which is 100% water).
. . We add: . gallons of water.
Write this in the second row.
. .
The final mixture has gallons which is 25% water.
. . It contains: . gallons of water.
Write this in the third row.
. .
Read down the last column.
We start with 25 gallons of water, then add gallons of water.
. . Hence, the mixture contains gallons of water. [1]
Read across the last row.
We have gallons which is 25% water.
. . Hence, the mixture contains gallons of water. [2]
We just described the final amount of water in two ways.
There is our equation!
Got it?