Ni : Zn: Cu = 7:2:9 =7x : 2x : 9x
7x+2x+9x = 3.8
18x=3.8
x=3.8/18=1.9/9≈0.21
Ni: 7x=7*0.21=1.47 ≈1.5 kg
Zn: 2x=2*0.21=0.42≈0.4 kg
Cu: 9x=9*0.21=1.89 ≈1.9 kg
Check 1.5+0.4+1.9 =3.8 True
The elimination method is a sufficient way to solve problems.
2x+y= 20
6x-5y=12
Add 5y to the one equation.
2x+6y= 20
6x= 12
Subtract 2x from both sides.
6y= 20
4x= 12
Divide 6 by 20.
y= 3.3
Divide 4 by 12.
x= 3
I hope this helped you!
Brainliest answer is appreciated!
Answer:
30% students
Step-by-step explanation:
Let x be the number of total students of a school.
63% are girls then total number of girls = (0.63)x
37% are boys then total number of boys = ( 0.37)x
Now 23% of girls wear contacts then total number of girls
= (0.63x) × 0.23
= (0.1449x)
And 42% of boys wear contacts then total number of boys wearing contacts
= (0.37x) ( 0.42)
= (0.1554)x
Total students wears contacts = ( 0.1449x) + (0.1554x)
= (0.3003x)
Percentage of students wear contacts = 
× 100
= 
× 100
= 30%
All 30% students wear contacts.
Answer:
Subtract property of deviation becasue your subtracting 6y frrom both sides of the equation.
Step-by-step explanation:
1)Given: 12y - 40 - 4y = 6y - 18
2)Simplify by adding 12y + (-4y): 8y - 40 = 6y - 18
3)Subtract property of deviation: 8y -6y - 40 = 6y -6y - 18
2y - 40 = -18
<em>Hope this helped!</em>
Multiply top by top
2 * -3 = -6
Multiply bottom
7 * 8 = 56
The answer is -6/56
Simplify = -3/28
