# Substitution word problem

• Jan 21st 2008, 05:45 PM
questions4u
Substitution word problem
I realise I posted this in the wrong forum sorry:(

the problem is:
a silversmith has alloys that contain 40% silver and others that have 50% silver. A custom order requires 150g of 44% silver. How much of each alloy should be melted together to make the bracelet?

so far i got:
Let x represent the 40% alloy
Let y represent the 50% alloy.

x+y=150
0.4x+0.5y=0.44

I rearranged the first eqaution to be y=-x+150.
Then subbed it into the second to be 0.4x+0.5(-x+150)=0.44
but when I solved this, i got 745.6. Where did I go wrong?
• Jan 21st 2008, 06:23 PM
Jhevon
Quote:

Originally Posted by questions4u
I realise I posted this in the wrong forum sorry:(

the problem is:
a silversmith has alloys that contain 40% silver and others that have 50% silver. A custom order requires 150g of 44% silver. How much of each alloy should be melted together to make the bracelet?

so far i got:
Let x represent the 40% alloy
Let y represent the 50% alloy.

x+y=150
0.4x+0.5y=0.44

I rearranged the first eqaution to be y=-x+150.
Then subbed it into the second to be 0.4x+0.5(-x+150)=0.44
but when I solved this, i got 745.6. Where did I go wrong?

your second equation is wrong. it should be equated to 66 (which is 44% of 150g) not 0.44. you let x and y represent the grams of silver in the first equation and then the percentage of silver in the second. this inconsistency gave rise to your incorrect solution
• Jan 21st 2008, 07:35 PM
questions4u
thank you