A tree was planted in Balingshan forest farm this year, and B tree survived, with a survival rate of ()

A tree was planted in Balingshan forest farm this year, and B tree survived, with a survival rate of ()

A tree was planted in Balingshan forest farm this year, and B tree survived. The survival rate was (B / a)
B out of a

A school planted 20% more trees this year than last year, 5 hectares less than last year. How many hectares were planted last year?

A: we planted 25 hectares of trees last year

80 hectares of trees were planted last year, 20% less than this year. How many hectares are planted this year?

Let this year be X
Then (1-20%) x = 80
Get x = 100 ha