Well if the alloy makes the 1000 grams, but you are dealing with copper that isn't even 100% copper, than you either need 55% more copper, which isn't given, which means you really need 550 grams of alloy copper.
Answer:
20 longs, 9 units more than the 9 flats
Step-by-step explanation:
If Abby has 9 flats, she has 900 blocks of the 1109 she needs. The remaining 209 can be represented by ...
20 longs
9 units
_____
<em>Comment on the question</em>
We cannot see the model Abby has put together so far, so we don't know exactly what it takes to finish it. Any longs or units she already shows must be subtracted from the numbers above.
Answer:
x = friends that paid discount price = 8
y = friends that paid regular price = 4
Step-by-step explanation:
Let
x = friends that paid discount price
y = friends that paid regular price
x + y = 12 (1)
6x + 8y = 80 (2)
From (1)
x = 12 - y
Substitute x = 12 - y into (2)
6x + 8y = 80 (2)
6(12 - y) + 8y = 80
72 - 6y + 8y = 80
- 6y + 8y = 80 - 72
2y = 8
y = 8/2
y = 4
Substitute y = 4 into (1)
x + y = 12 (1)
x + 4 = 12
x = 12 - 4
x = 8
x = friends that paid discount price = 8
y = friends that paid regular price = 4
<span>5x - y = 15 (1)
-10x+2y=-30 (2)
multiply (1) by 2
10x - 2y = 30
</span>-10x + 2y = -30 (2)
<span>---------------------------add
0 = 0
answer
</span><span>infinitely many solutions</span><span>
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