What’s the answer to this

The transitive property of equality states that: o if a = b, then bra o if a = b, then ac = bc o if a = b and b= c, then a = if a = b and c= c, then a + b = b + c

Which of the following expressions is equal to 2x^2+8

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.