Multiply the number by 4. Add 10 to the product. Divide this sum by 2. Subtract 5 from the quotient. The first number is 1 and the result is 2

The second number is 5 and the result is 10

the third number is 9 and the result is 18

the fourth number is 10 and the result is 20

Write a conjecture that relates the result of the process to the original number selected. part a)

Represent the original number as n.

Answer is 2n

part b Represent the original number as n, and use deductive reasoning to prove the conjecture in part (a). Multiply the number by 4.

Help with part b please.