How do you combine #(5a + 7b + 9c) - (5a + b + 2c)#? Algebra Polynomials and Factoring Addition and Subtraction of Polynomials 1 Answer Don't Memorise Jul 23, 2015 #=color(blue)(6b+7c# Explanation: #5a+7b+9c−5a - b - 2c# Grouping like terms #(5a - 5a) +(7b - b) + (9c - 2c)# #=color(blue)(6b+7c# Answer link Related questions How do you add two polynomials? How do you subtract two polynomials? How do you add and simplify #3x^2-4x+7# and #2x^3-4x^2-6x+5#? How do you subtract #5b^2-2a^2# from #4a^2-8ab-9b^2#? How do you simplify #(6.9a^2-2.3b^2+2ab)+(3.1a-2.5b^2+b)#? How do you simplify #(-t+15t^2)-(5t^2+2t-9)#? How do you subtract #(-5m^2-m)-(3m^2+4m-5)#? How do you add two polynomials if they don't have like terms? How do you simplify #(3a+4b)-(-6a-3b)#? How do you subtract #(x^2-8x+7)-(6x^2+7x-3)#? See all questions in Addition and Subtraction of Polynomials Impact of this question 1449 views around the world You can reuse this answer Creative Commons License