[section 6][combining like terms]

Combine like terms:

(1.) 3a + 2a + 4 here is the problem

= 5a + 4 combine like terms

(2.) 8x + 3x + 9 here is the problem

= 11x + 9 combine like terms

(3.) 4a - b - 7b here is the problem

= 4a - 8b combine like terms

(4.) 2m + 7m - 8m here is the problem

= m combine like terms

(5.) 12x - 3y + x + 2y here is the problem

= 13x - y combine like terms

(6.) 8rt + 3rt + t - 3t here is the problem

= 11rt - 2t combine like terms

(7.) 5x + 7x - 6y here is the problem

= 12x - 6y combine like terms

(8.) 4y - y + 8 here is the problem

= 3y + 8 combine like terms

(9.) 15 + 9y - 4y here is the problem

= 15 + 5y combine like terms

(10.) 19m - m - 3n + 2n here is the problem

= 18m - n combine like terms