Form four expressions using $y$, $2$ and $7$. Every expression must have $y$ in it. Use only two number operations. They should be different​.

Hint: We have to form four expressions using $y$, $2$ and $7$. Also, every expression must have $y$ in it and we have to use only two number operations. So try it with the applied conditions.

Complete step-by-step answer:
We have to form four expressions using $y$, $2$ and $7$. Also, every expression must have $y$ in it and we have to use only two number operations.
Now let us take $2y+7$, $2y-7$, $2+7y$, $2-7y$, $\dfrac{y}{2}-7$ etc.
So we can see the above expressions which satisfy all the conditions.

Additional information:
An algebraic expression in mathematics is an expression which is made up of variables and constants, along with algebraic operations (addition, subtraction, etc.). Expressions are made up of terms.
$3x+4y-7,4x-10$, etc.
These expressions are represented with the help of unknown variables, constants and coefficient. The combination of these three (as terms) is said to be an expression. It is to be noted that, unlike the algebraic equation, an algebraic expression has no sides or equal to sign.
An algebraic expression which is having only one term is known as a monomial. A binomial expression is an algebraic expression which has two terms, which are unlike. In general, an expression with more than one terms with non-negative integral exponents of a variable is known as a polynomial.
A numeric expression consists of numbers and operations, but never includes any variable. A variable expression is an expression which contains variables along with numbers and operations to define an expression.

Note: We have given the conditions, so we have written expressions in such a way that all the conditions are taken into consideration. Keep in mind that y should be present in all expressions.