We know there are 2 L per tick, and the water reaches above 20 but below 30... so that mean the water's in it's 20's.
There are 4 ticks, so 2 * 4 = 8L.
20 + 8 = 28L in Jose's container.
We know that there are 2L per tick, so shade it to the 40, and shade in 2 more ticks, because 2 * 2 = 4. And Jackson needs 44 ticks.
Basically shade it to the 40 mark. Then shade in 2 more ticks.