Question

Use a system of equations to solve this problem.

Bronze is a mix, or alloy, of tin and copper. A metal worker needs 100 g of bronze that is 25% tin. He has one tin/copper alloy that is 5% tin and another tin/copper alloy that is 45% tin.
Let x = the number of grams of the 5% tin alloy.
Let y = the number of grams of the 45% tin alloy.
How many grams of each alloy should the metal worker combine?
Enter your answers into the boxes.
__g of the 5% tin alloy and __g of the 45% tin alloy.

Answer 1

50g of the 5% tin alloy

and also

50g of the 45% tin alloy

Explanation:

I took the k12 test

Answer 2

Those are the two equations:

x+y=100
the sum of the weight of both alloys is 100 g

0.5x+0.45y=0.25*100
the sum of the weights of tin has to be 25% of 100g, which is actually 25 g
0.5x+0.45y=25


So we have:
x+y=100
0.5x+0.45y=25

x=10-y
0.5x+0.45y=25

We substitute:
0.5(10-y)+0.45y=25

We calculate:

5-0.5y+0.45y=25
-0.5y+0.45y=20
0.4y=20
4y=200
y=50

So he needs 50 grams of 45% alloy and 100-50=50 grams of tin alloy as well