1. Resuelve los siguientes ejercicios:
a. Sumar $-2x+4ycon6x+9y$
b. Sumar $-7x+9x^{2}con$ $4x^{2}+18x$
c. Sumar $x-1con$ $3x-3$
d. Sumar $a^{2}-2ab+6b^{2}con-a^{2}+2ab-6b^{2}$
e. Sumar $4c^{2}d-8cd$ $con$ $-9c^{2}d+5cd^{2}$
$t.$ Sumar $-3x^{2}+8x^{2}-6x+1con$ $19x^{2}+4x^{3}-9x+16$
$g$ Sumar $6a^{2}+9a+8cona^{3}+5a+13$
h. Sumar $4m^{2}n+6mn^{2}+m^{3}conn^{3}+15m^{2}n-20mn^{2}$
$1.S$ Sumar $-11tx+18t^{2}$ $-25x^{2}con$ $10t^{2}-54x^{2}+27α$