The first tank is 300 liters filled while the second tank is 450 liters filled. The second tank is only 45% filled. If the two tanks have the same capacity, how many more liters of water are needed to fill the two tanks?
Since 450 liters represents 45%, then each 1% is equal to 450 liters/45 = 
<gadget id="calculator">450/45</gadget>
<output>10</output>
10 liters.
Hence, the capacity of each tank is 10 liters x 100 = 
<gadget id="calculator">10*100</gadget>
<output>1_000</output>
1000 liters.
So, the first tank needs 1000 - 300 = 
<gadget id="calculator">1000-300</gadget>
<output>700</output>
700 liters of water more.
While the second tank needs 1000 - 450 = 
<gadget id="calculator">1000-450</gadget>
<output>550</output>
550 liters more.
Therefore, 700 + 550 = 
<gadget id="calculator">700+550</gadget>
<output>1_250</output>
1250 liters of water are needed to fill the two tanks.

<result>1_250</result>