10-x-3x=7x-23
i need with this question it is too hard

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

Prove that quadrilateral is a rhombus.

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