Example 1:
$$ \textup{Find the sum of} \; 3x \; \textup{and} \; 4x$$Solution:
$$ 3x + 4x = 7x$$Example 2:
$$ \textup{Find the sum of} \; 7a \; \textup{and} \; 5a$$Solution:
$$ 7a + 5a = 12a$$Example 3:
$$ \textup{Find the sum of} \; 5x \; \textup{and} \; -2x$$Solution:
$$ 5x + (-2x) = 5x - 2x = 3x$$Example 4:
$$ \textup{Find the sum of} \; 8x \; \textup{and} \; x$$Solution:
$$ 8x + x = 9x$$Example 5:
$$ \textup{Find the sum of} \; 4a, \; a \; \textup{and} \; 10a$$Solution:
$$ 4a+a+10a=15a$$Example 6:
$$ \textup{Find the sum of} \, -3c, \, -5c, \, -2c \, \textup{and} \, -8c$$Solution:
$$ (-3c)+(-5c)+(-2c)+(-8c) $$ $$ =-3c-5c-2c-8c $$ $$ =-18c $$Example 7:
$$ \textup{Simplify} \; 3x+2y+7x+5y $$Solution:
$$ 3x+2y+7x+5y $$ $$ =3x+7x+2y+5y $$ $$ =10x+7y $$Example 8:
$$ \textup{Simplify} \; 8x+9+4x+15$$Solution:
$$ 8x+9+4x+15 $$ $$ =8x+4x+9+15 $$ $$ =12x+24 $$Example 9:
Simplify
$$ 3a+2b+4c+4a+3b+c+5a+b+8c$$