<span>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.</span>
The maximum area of a rectangle results from it being a square. The rectangle (or square) must have 4 equal sides in order to maximize area. But in this case, one side is a wall. That means that the remaining three sides will be = 60 / 3 = 20 feet long. You formed an square that is 20 ft x 20 ft = 400 ft²
