Measure carefully. Make the target. Keep an eye on cost.
Assumption: volumes add when solutions mix, and their strengths combine by volume.
Adjust the mixture or choose a supplier.
Orange: mixture strength · Pink: your proposed mix · Green dashed: target
Dilution: concentrate volume = total volume × (concentrate parts ÷ all parts). The remaining volume is water.
Alligation: for strengths A, B and target T, the mixing ratio A:B is |B − T| : |T − A|. This works only if T lies between the two source strengths.
Unit price = dollars ÷ quantity. Mark-up percentage compares the increased selling price with the original cost.