Answer:
x = 7
Step-by-step explanation:
The proportion is
14/6 = 21/(3x - 12) Cross Multiply
14*(3x - 12) = 6*21 Remove the brackets and combine
42x - 168 = 126 Add 168 to both sides
42x = 126 + 168
42x = 294 Divide by 42
x = 294/42
x = 7
Answer:
Mr.Lin's present age is 30 years now. His son is 8 years old now.
Step-by-step explanation:
Let L = Mr.Lin's present age,
S = his son's present age.
First equation is
L + S = 38. (1)
The second equation is
L + 3 = 3*(S+3) (2) ("In three years' time, Mr.Lin will be three times as old as his son.")
From (1), express S = 38-L and substitute it into (2). You will get
L + 3 = 3*((38-L)+3), or
L + 3 = 114 - 3L + 9,
4L = 114 + 9 - 3,
4L = 120,
L = 30.
7/3x+1/3x=3x+6/3+5/3x
8/3x-5/3x=3x+6/3
3/3x=3x+6/3
x=3x+6/3
x-3x=6/3
-2x=2
-x=2/2
-x=1
x=-1
Answer:
I think A is the answer
Step-by-step explanation:
Comment down if I am wrong but if I am right give me stars or a thank you or a thank you comment.
Answer:
Note: The expression "h =300- pi r /pi r" would equate to 299, as written. I find h = (300 - π
)/πr to be the equation for height.
Step-by-step explanation:
The total surface area of a sylinder is 2πr(h+r) where h is the height and r is the radius. That consists of top and bottom disks, each with an area of π, for a total of 2π. The side is a continous sheet that has an area of 2πrh, where h is the height. 2πr is the circumference of the can, so the surface area of the side is 2πrh.
The total surace area of a closed cylinder is therefore 2π + 2πrh.
2π + 2πrh = 600
π + πrh = 300
πrh = 300 - π
h = (300 - π )/πr
