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.
1/2(4y+7)
Use the distributive property. a(b+c)= ab+ac
1/2*4y= 2y
1/2*7= 3.5
2y+3.5 <---- simplified expression
I hope this helps!
~kaikers
Answer:
a. -7 + 3
b. draw 7 negatives + 7 positives
Step-by-step explanation:
Answer:
The point where the line crosses the x-axis is called the [x-intercept].
Step-by-step explanation:
23 units sure does hope this helps
