Question

how do you add and subtract algebraic expressions??

Answer 1

like terms get added and substracted
like 
a + a = 2a 
a + b = will same as it is that is 
a + b = a + b
as unlike terms dont add
a + a + b + b + c = 2a + 2b + c

a - a = 0
a - b will give 
a - b = a - b
2a + b - a + b - c + 2a 
= 3a + 2b - c

Answer 2

like terms can be added
such as :the powers ,variables must be the same then we can add or subtract algebraic expression