The answer should be 5 or -5
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:
x=−y−1
Step-by-step explanation:
y=−x−1
Step 1: Flip the equation.
−x−1=y
Step 2: Add 1 to both sides.
−x−1+1=y+1
−x=y+1
Step 3: Divide both sides by -1.
−x
−1
=
y+1
−1
x=−y−1
The square of a whole number n lies between 80 and 150, so n lies between √80 and √150.
n is a whole number and lies between 8.9 and 12.2, so n can be 9, 10, 11, or 12.
The possible values for n are 9, 10, 11, and 12.
