Can you please help me solve this

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

If x-1 and x+3 are the factors of x3+10x2+ax+b find a and b

Plzzz answer both questions and i will give you 100 points