Ametal alloy is a metal made by blending 2 or more types of metal. a jeweler has supplies of two metal alloys. on alloy is 30% gold and the other is 10% gold. how much of each alloy should the jeweler combine to create 4kg of an alloy containing 15% gold?

He should combine 1 kg of 30% alloy and 3 kg of 10% alloy.

Step-by-step explanation:

Let x = mass of 30% ally.

Let y = mass of 10% alloy.

He needs 4 kg of alloy, so the first equation, dealing with masses, is

x + y = 4

Now we deal with the amount of gold.

He uses x mass of 30% gold alloy. The amount of gold in that mass is 0.3x.

He uses y mass of 10% gold alloy. The amount of gold in that mass is 0.1y.

The total mass of gold is 0.3x + 0.1y. We are told the told the end alloy is 4 kg of 15% gold alloy. That contains 0.15(4) kg = 0.6 kg of gold.

The second equation is

0.3x + 0.1y = 0.6

Now we put together the two equations as a system of equations.

x + y = 4

0.3x + 0.1y = 0.6

Multiply both sides of the second equation by -10.

-3x - y = -6

Add this equation to the first original equation.

         x + y = 4

+     -3x - y = -6

        -2x    = -2

            x    = 1

Now substitute x = 1 in the first original equation and solve for y.

x + y = 4

x + y = 4

y = 3

He should combine 1 kg of 30% alloy and 3 kg of 10% alloy.

step-by-step explanation:

y = | -2(-2) |     →     y = | 4 |     →     y = 4       ⇒   (-2, 4)

y = | -2(-1) |     →     y = | 2 |     →       y =   2       ⇒   (-1, 2)    

y = | -2(0) |     →     y = | 0 |     →       y = 0         ⇒   (0, 0)

y = | -2(1) |   c →     y = | -2 |     →     y =   2         ⇒   (1, 2)    

y = | -2(2) |     →     y = | - 4 |     →     y =   4         ⇒   (2, 4)  

your answer would be 12