What weight of dry substance is in 150g of a 3% substance solution? What weight of an 8% solution can we have with the same weight of dry substance?

4.5 g 56.25 g Since the only type of measurement mentioned in this question is weight or mass, I'll assume that the percentage concentration is % m/m (mass/mass). For that type of concentration measurement, simply multiple the percentage by the total mass to get the mass of the desired substance. So 150 g * 3% = 150 g * 0.03 = 4.5g For the amount of 8% solution with the same amount of dry substance, there's 2 ways of calculating the mass of solution. First, use the ratio of percentages, multiplied by the mass of the original solution to get the desired amount of new solution: 3/8 * 150 g = 56.35 g Or calculate it from scratch, like 4.5/X = 8/100 450/X = 8 450 = 8X 56.25 = X In both cases, the result is that you desire 56.25 grams of 8% solution.