(2) Sunshine Middle School used 0/50 tons of water in April, 30 tons less than that in March, so the water consumption in April was 5/6 (5/6) of that in March.

(3) Xiaoming is 12 years old this year, and Xiaojie is three years older than him. Three years later, Xiao Ming is 5/6 (5/6) of Xiaojie's age.

(4) The original price of a refrigerator is 2,500 yuan, and now it is supplied in 250 yuan at a reduced price. The current price is 9/ 10 (nine tenths) of the original price.