Answer:
25.6 grams of the second ingredient (25% protein) to make 28 grams of the mixture that is 30% protein.
Explanation:
To make 28 grams of a substance that is 30% protein, Becky will need to mix together different ingredients to get the desired amount of protein.
Let's call the amount of the first ingredient (50% protein) "x" and the amount of the second ingredient (25% protein) "y".
We know that:
The total amount of the mixture is 28 grams
The mixture is 30% protein
The first ingredient is 50% protein
The second ingredient is 25% protein
We can set up the following equations to represent the problem:
x + y = 28 (the total amount of the mixture is 28 grams)
(0.50)x + (0.25)y = 0.30(28) (the mixture is 30% protein)
Now we can use the first equation to solve for one variable in terms of the other. If we solve for y, we get:
y = 28 - x
We can substitute this into the second equation:
(0.50)x + (0.25)(28-x) = 0.30(28)
Which gives us:
0.50x + 7 - 0.25x = 8.4
And further simplifying
0.25x = 0.6
x = 2.4
Now we know that the first ingredient, which is 50% protein, makes up 2.4 grams of the mixture. We can use this information to find the amount of the second ingredient:
y = 28 - x = 28 - 2.4 = 25.6 grams
So, Becky needs to use 2.4 grams of the first ingredient (50% protein) and 25.6 grams of the second ingredient (25% protein) to make 28 grams of the mixture that is 30% protein.