Answer:
12 cups of salad
Explanation:
Let the unknown cups of salad in the mixture be x( unknown cup in 55% mixture)
Thus, we have the following expression that shows the number of salad in the resulting mixture;
4(40%) + x(55%) = (4+x)(50%)
= 0.4(4) + x(0.55) = 0.5(4 + x)
= 1.6 + 0.55x = 0.2 + 0.5x
0.2 -1.6 = 0.55x-0.5x
0.4 = 0.05x
x = 0.4/0.05
x = 8 cups of salad
So the number of salad cups in the resulting mixture = x + 4 = 8 + 4 = 12 cups of salad