Check whether the following is an equation or not. If it is equation, then identify the variable in an equation.

$40-\left(20-10\right)=6\times 5$

Check whether the following is an equation or not. If it is equation, then identify the variable in an equation.

$20=5y$

Check whether the following is an equation or not. If it is equation, then identify the variable in an equation.

$\frac{4q}{3}<7$

Check whether the following is an equation or not. If it is equation, then identify the variable in an equation.

$5m-3=12$

Pick out the solution from the values given in the bracket next to equation. Show that the other values do not satisfy the equation.

$x+4=11$,      $\left(8, -7, 7, 11\right)$

Pick out the solution from the values given in the bracket next to equation. Show that the other values do not satisfy the equation.

$3x+7=22$,      $\left(7, 5, -7, -5\right)$

Pick out the solution from the values given in the bracket next to equation. Show that the other values do not satisfy the equation.

$\frac{m}{3}=2$,      $\left(3, 1, 6, -2\right)$

Pick out the solution from the values given in the bracket next to equation. Show that the other values do not satisfy the equation.

$4y-2=18$,      $\left(4, 5, -4, -5\right)$