To find the simpliest form of a fraction, all you need to do is divide the numerator and denominator by their greatest common factor, in which in this case, is 2. And so all you need to do is divide the numerator(42) and the denominator(50) by 2, to get 21/25. This means that the simpliest form of 42/50 is 21/25.
Polynomial are classified according to their number of terms. 5x^3+8y+6x^2 has three terms, 2xy has 1 term and 15-y^2. A polynomial with 1 term is called a monomial, A polynomial with 2 terms is called a binomial while a polynomial with 3 terms is called a trinomial. Thus our polynomial 2x^4+6x-3 is called a trinomial.
Given:
There exist a proportional relationship between x and y.
To find:
The equation which represents a proportional relationship between x and y.
Solution:
If there exist a proportional relationship between x and y, then


where, k is constant of proportionality.
We know that, proportional relationship passes through the origin because (0,0) satisfy
.
For x=0, check which equation has y=0.
In option A,
.
In option B,
.
In option C,
.
In option D, 
Only in option C, we have a equation of the form
with 4 as constant of proportionality and it passes through (0,0).
Therefore, the correct option is C.