Substitution is where we first Isolate one of the unknowns, express it in terms of the other unknown, and replace the isolated unknown with the other unknown in another equation. So that each time we only need to deal with one unknown. I think you'll get a better idea here:
First name these 2 equations with 1 and 2.
4x + 5y = 7 (1)
y = 3x + 9 (2)
Since y is already isolated in (2), so we can skip the isolation step and continue to substitute.
Substitute (2) into (1).
4x + 5(3x+9) = 7
Expand.
4x + 15x + 45 = 7
Group.
19x + 45 = 7
Shift +45 to the other side and turn it into -45.
19x = 7 - 45
19x = -38
Shift x19 to the other side, turn it into /19.
X = - 38/19
X = - 2
Now we solved x already, we can just substitute x= - 2 back to equation (2).
y = 3(-2) + 9
y = - 6 + 9
y = 3
So, the answers are
x = - 2
y = 3
Answer:
B. 41 feet per year
Step-by-step explanation:
943/23= 41
Total feet / coefficient= feet per year
Answer:
3 is greater than -4, but the line with slope -4 is steeper than the line with slope 3.
Step-by-step explanation:
3 is greater than -4, so strictly speaking, a slope of 3 is greater than a slope of -4.
On the other hand, the steepness of a line depends on the absolute value of the slope.
|3| = 3
|-4| = 4
Since 4 > 3, the line with slope -4 is steeper than the line with slope 3.
Answer: 3 is greater than -4, but the line with slope -4 is steeper than the line with slope 3.
The variation of K is what is found in front of X
Surface area of the cylinder = 816.4 sq. ft.
Solution:
Height of the cylinder = 21 ft
Diameter of the cylinder = 10 ft
Radius of the cylinder = 10 ÷ 2 = 5 ft
Use the value of 
= 3.14
Surface area of the cylinder = 
Substitute the given values in the surface area formula, we get
Surface area of the cylinder 
ft²
Hence the surface area of the cylinder is 816.4 sq. ft.
