randVar() randRange(1, 29) randRange(A + 1, 30)

Solve for `X`:

`X=` B - A

`A + X = B`

Subtract `A` from both sides:

`\qquad \begin{eqnarray} A + X &=& B \\ \\ A + X \red{- A} &=& B \red{- A} \end{eqnarray}`

`X + A = B`

Subtract `A` from both sides:

`\qquad \begin{eqnarray} X + A &=& B \\ \\ X + A \red{- A} &=& B \red{- A} \end{eqnarray}`

`B = A + X`

Subtract `A` from both sides:

`\qquad \begin{eqnarray} B &=& A + X \\ \\ B \red{- A} &=& A + X \red{- A} \end{eqnarray}`

`B = X + A`

Subtract `A` from both sides:

`\qquad \begin{eqnarray} B &=& X + A \\ \\ B \red{- A} &=& X + A \red{- A} \end{eqnarray}`

Simplify.

`\qquad X = B - A`