Answer:
Step-by-step explanation:
Try breaking these into sections.
Twice: 2 times
The sum of: add
A number: choose a variable, like x
---Thus "the sum of a number and 4" becomes "add x and 4" which, mathematically, is "x+4"
-----Continuing to put it all together, "Twice the sum of a number and four" becomes "2 times (x+4)" which, mathematically, is "2(x+4)"
Is: equals
-------"Twice the sum of a number and four is" becomes "2(x+4)="
23 less than: subtract 23. This one tends to trick people; "23 less than" will become "__ - 23", NOT "23 - __"
three times the number: 3 times x
---"23 less than three times the number" becomes "subtract 23 from 3 times x" which, mathematically, is "3x-23"
-------So the final phrase: 2(x+4)=3x-23"
The surface area is made up of six sides and the area is then just the sum of the areas of the six sides...
A=2xy+2xz+2yz
A=2(xy+xz+yz) in this case:
A=2(5*4.5+5*3.5+4.5*3.5)
A=2(22.5+17.5+15.75)
A=2(55.75)
A=111.5 in^2
The length of the rectangle is = 72 cm
The width of the rectangle is = 56 cm
Area of the rectangle is = 
= 
cm²
As given, the other rectangle has the same area as this one, but its width is 21 cm.
Let the length here be = x
Hence, length is 192 cm.
We can see that as width decreases, the length increases if area is constant and when length decreases then width increases if area is constant.
So, in the new rectangle,constant of variation=k is given by,
or 
Hence, the constant of variation is 
