What is the series in Sigma notation ABC or D

Leo has b boxes of pencils. each box contains 6 pencils. he has a total of 42 pencils. the equation that represents this situation the value of b that makes the equation true the first one is b+6=42,6b=42,b=42+6,or 42b=6 the second one are 7,836 48

What multiplys to be 1 but adds up to be 4

Add: (6x^2-5x+3) + (3x^3+7x-8) a. 9x^2+12x-5 b. 9x^2+2x+11 c. 9x^2+2x-5 d. 9x^2-2x+5