Answer: 27
Step-by-step explanation:
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.
<h3>
Answer: 19 dimes</h3>
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Work Shown:
d = number of dimes
q = 32-d = number of quarters
$5.15 = 515 cents
10d+25q = 515
10d+25(32-d) = 515
10d+800-25d = 515
-15d+800 = 515
-15d = 515-800
-15d = -285
d = -285/(-15)
d = 19
There are 19 dimes. You can stop here if you want.
q = 32-d = 32-19 = 13
There are 13 quarters
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Check:
1 dime = 10 cents
19 dimes = 19*10 = 190 cents
1 quarter = 25 cents
13 quarters = 13*25 = 325 cents
total value = 190 cents + 325 cents = 515 cents = $5.15
The answer is confirmed.
-10 is equal to 5 subtracted from a number
Assume that the number is x
So the equation will be
we put x at first because in subtraction the number after the word "from" comes first
Now let us find x
We need to move 5 to the left side to find x, so add 5 to both sides
The number is
Answer:
3
Step-by-step explanation:
6 times 3 equals 18
