18 kg of 15% copper and 72 kg of 60% copper should be combined by the metalworker to create 90 kg of 51% copper alloy.
<u>Step-by-step explanation:</u>
Let x = kg of 15% copper alloy
Let y = kg of 60% copper alloy
Since we need to create 90 kg of alloy we know:
x + y = 90
51% of 90 kg = 45.9 kg of copper
So we're interested in creating 45.9 kg of copper
We need some amount of 15% copper and some amount of 60% copper to create 45.9 kg of copper:
0.15x + 0.60y = 45.9
but
x + y = 90
x= 90 - y
substituting that value in for x
0.15(90 - y) + 0.60y = 45.9
13.5 - 0.15y + 0.60y = 45.9
0.45y = 32.4
y = 72
Substituting this y value to solve for x gives:
x + y = 90
x= 90-72
x=18
Therefore, in order to create 90kg of 51% alloy, we'd need 18 kg of 15% copper and 72 kg of 60% copper.
3 days they with both have 4 dollars
Answer:
Seven plus 2 divided by a number
Step-by-step explanation:
I think thats what u meAn
Answer:
9/7is the chance of coming red ball
Answer:
0.12 x (x + 3000) = 4200
equation for her salary last year : last year's salary = (4200 / 0.12) - 3000
$32,000
Step-by-step explanation:
Let x = last year's salary
this year's salary = 3000 + x
this equation can be used to determine how much she saved this year = 0.12 x (x + 3000) = 4200
to find last year's salary, make x the subject of the formula
4200 / 0.12 - 3000 = x
x = $32,000
