Answer: 9/4n
Step-by-step explanation:
Let's take T to represent tank
When n litres of fuel was added to tank that was 1/3 full = n + 1/3T
The tank was 7/9T
n+1/3T = 7/9T
n =7/9T - 1/3T
n = 4/9
If a full tank is taken to be 1 = 9/9
Hence, we will have 1 = x × n
1 = x × 4/9
x = 9/4
Hence 9/4 of n = 9/4n