Identify the like terms in the following algebraic expression:

${\mathrm{a}}^2+{\mathrm{b}}^2-2{\mathrm{a}}^2+{\mathrm{c}}^2+4\mathrm{a}$

Identify the like terms in the following algebraic expression:

$3x+4xy-2yz+\frac{5}{2}zy$

Identify the like terms in the following algebraic expression:
$\mathrm{abc}+{\mathrm{ab}}^2\mathrm{c}+2{\mathrm{acb}}^2+3{\mathrm{c}}^2\mathrm{ab}+{\mathrm{b}}^2\mathrm{ac}-2{\mathrm{a}}^2\mathrm{bc}+3{\mathrm{cab}}^2$

Write the coefficient of $x$ in $-12x$.

Write the coefficient of $\mathrm{x}$ in the following:
$-7\mathrm{xy}$

Write the coefficient of $\mathrm{x}$ in the following:
$\mathrm{xyz}$

Write the coefficient of $\mathrm{x}$ in the following:
$-7\mathrm{ax}$

Write the coefficient of ${\mathrm{x}}^2$ in the following:
$-3{\mathrm{x}}^2$

Write the coefficient of ${\mathrm{x}}^2$ in the following:
$5{\mathrm{x}}^2\mathrm{yz}$