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.
Answer:
Yes its correct the unhighlighted is complement
Hello! $200 is the fixed amount. B doesn't have 200 as part of the problem, so B is eliminated. A is also out, because you add, not subtract. 100 is the amount of boots made, not the amount made per pair of boots. 100 would be the value of "x". The cost per day is $9,200, and 9,200 - 200 is 9,000. With 100 pairs of boots being made each day, 9,000/100 is 90. It would cost $90 per pair of boots made, with the variable "x" being beside it. The correct equation would be C(x) = 90x + 200. The answer is D.
