In the context of the equation that Marco uses to calculate the tree's height \( h \), the variable \( x \) typically represents the number of years since the tree was planted.
Given that the tree was initially 54 inches tall and grows at a rate of approximately 1.5 inches per year, the equation for the tree’s height over time could be expressed as:
\[ h = 54 + 1.5x \]
In this equation:
- \( h \) is the height of the tree in inches.
- \( 54 \) is the initial height of the tree.
- \( 1.5 \) is the growth rate in inches per year.
- \( x \) is the number of years since the tree was planted.