Having problems with this volume question.

There were 68000cm3 of water in tank X and tank Y. The heights of the water in both tanks are equal. Tank Y was 40% full of water. When all the water from tank Y was poured into tank X, 4litres of water overflowed.

A) find the height of the water in tank X at first?

B) find the capacity of tank Y?

Thanks in advance