Evaluate: $2m^2+8n$ for  $m=-2$ and $n=6$.

Write an algebraic expression for: Add twice of $x$ and $y$.

Solve: $-(-2b-\left(3b+4c\right)$.

Write algebraic expression: Subtract $4$ from thrice of $y$.

Evaluate $3m^2+2m^{2}n+n^2$ for $m=-1$ and $n=1$.

Solve: $-\left(49-a^2\right)-5a^2$.

Solve the crossword, on the basis of clues mentioned below. 

Across
$1.$ A polynomial of degree two
$5.$ Degree of $7m-7$
$7.$ Degree of a non-zero constant polynomial
$8.$ $4$ in $4x+3$
$9.$ $x$ and $8$ in $x-8$

Down
$2.$ The highest power of variable
$3.$ $5$ is....... polynomial
$4.$ A polynomial that has two terms
$6.$ A polynomial of degree one
$9.$ Degree of $5t^2-7t+1$

Given a general expression $2n-3$, where $n$ is a natural number. Write the first four numbers in the number pattern.

Given a general expression $4n-1$, where $n$ is a natural number. Write the first four numbers in the number pattern.