Using the variable 'J' for the height of Jackson, we know that Elliott is Jackson's height, plus an additional 9 inches. Since Elliott is 64 inches tall in total, we can add Jackson's height plus 9 to get Elliot's height:
Jackson's height + 9 inches = Elliot's height
J + 9 = 63
Subtract '9' from both sides: J + 9 - 9 = 63 - 9 or J = 54
