Answer:
29
Step-by-step explanation:
(x+12) + 100 + x = 180
2x + 112 = 180
Subtract 112 from both sides
2x = 58
Divide 2 from both sides
x = 29
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.
Set up fractions and solve them
Answer – Always
A negative number raised to an odd power is always negative. When a negative number is raised to an even power, the pairs of negatives will cancel out; but when it is raised to an odd power, after pairs of the negative sign have canceled each other out, there will still be one minus sign left unpaired, which will not cancel out.
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The answer is 13/85. You could find out the answer by doing the reprical multiplication.
