To determine how many lawns Gio needs to mow to reach his goal of $900, we first need to calculate how much more money he needs to save.
- He currently has $250.
- His goal is to save $900.
Now, we subtract his current amount from his goal:
\[ 900 - 250 = 650 \]
Gio needs to save an additional $650.
Next, we know that he earns $25 for each lawn he mows. To find out how many lawns he needs to mow, we divide the amount he still needs by the amount he earns per lawn:
\[ \frac{650}{25} = 26 \]
Thus, Gio needs to mow 26 lawns to reach his saving goal of $900.