Answer:
40 hours
Step-by-step explanation:
Lets take "x" as the # of hours it takes the lava to reach the sea
since there is a lava flow of 0.5 kilos per hour
we will multiply "x" with 0.5
0.5x
now the tube system is 20 kilometers long
this means that at a rate of 0.5 kilos per hour the lava will reach the sea once it is 20 kilometers deep
so
0.5x=20
divide "0.5" by both sides to eliminate the coefficient

x=40
it will take 40 hours for the lava to reach the sea
Hope this helps!
Answer:
193650
Step-by-step explanation:
Since the cost must be no more than 387$, you can substitute that number instead of y to get 387 = 0.002x - 0.30. you can add 0.30 to both sides to get 387.3 = 0.002x
Then you can divide both sides by 0.002 to get 387.3/0.002 = 193650
Answer:
More earn this summer per month = $30 more
Entire summer earning (for 2.5 months) = $1950
Step-by-step explanation:
For 2.5 months, you got 1875 dollars, so per month salary is:
1875/2.5 = $750 per month
This summer, you got a 4% raise, that means:
4% = 4/100 = 0.04
The raise is:
0.04 * 750 = $30 raise
So, new monthly salary is:
750 + 30 = $780
So, assuming you will work 2.5 months again this summer, you total earnings would be:
2.5 * 780 = $1950
Answer:
y = 4
x = -1
Step-by-step explanation:
4x + 2y = 4 Eq. 1
3x - y = -7 Eq. 2
from the Eq. 2
3x = y - 7
3x + 7 = y Eq. 3
Replacing the value of the Eq. 3 in the Eq. 1
4x + 2(3x+7) = 4
4x + (2*3x + 2*7) = 4
4x + (6x + 14) = 4
10x + 14 = 4
10x = 4 - 14
10x = - 10
x = -10/10
x = -1
from the Eq. 3
3x + 7 = y
3*-1 + 7 = y
-3 + 7 = y
4 = y
Check:
from the Eq. 1
4x + 2y = 4
4*-1 + 2*4 = 4
-4 + 8 = 4