Answer: 20x+12
Step-by-step explanation:
Distribute the three: 3(7x+4) will be changed to 21x+12-x
Next group like terms, -x+21x=20x
The new equation will be 20x+12
The answer to the given question is as below:-
Polynomials:-
x³-7x²+9x-5x⁴-20
x⁵-5x⁴+4x³+2x-1
3x²-5x⁴+2x-12
Non-polynomial:-
x⁻5-5x⁻⁴+4x⁻³+2x⁻1-1

![\sqrt[4]{x} -\sqrt[3]{x} 4+\sqrt{x}-8x+16](https://tex.z-dn.net/?f=%5Csqrt%5B4%5D%7Bx%7D%20-%5Csqrt%5B3%5D%7Bx%7D%204%2B%5Csqrt%7Bx%7D-8x%2B16)
<h3>What are polynomials?</h3>
A polynomial is a mathematical equation made up of indeterminates and coefficients and involves only addition, subtraction, multiplication, and non-negative integer exponentiation of variables. The exponents of the polynomials can not be irrational.
So the table will be formed as:-
Polynomials:- Non-polynomial:-
x³-7x²+9x-5x⁴-20 x⁻5-5x⁻⁴+4x⁻³+2x⁻1-1
x⁵-5x⁴+4x³+2x-1 
3x²-5x⁴+2x-12 ![\sqrt[4]{x} -\sqrt[3]{x} 4+\sqrt{x}-8x+16](https://tex.z-dn.net/?f=%5Csqrt%5B4%5D%7Bx%7D%20-%5Csqrt%5B3%5D%7Bx%7D%204%2B%5Csqrt%7Bx%7D-8x%2B16)
Therefore the polynomials and non-polynomials are shown in the table above.
To know more about polynomials follow
brainly.com/question/2833285
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Amar's age = a
sister is a - 5
add both = 39
a + (a - 5) = 39
2a - 5 = 39
2a = 44
a = 22 and sister is 17