How to select one of two formulas depending on a IF-expression in LibreOffice Calc?

I want to implement something like that.

IF X < 1000 THEN
  Y = (1000-X) / 2 * 0.1 + 67

This doesn't work the way I expected.

=IF(A1 < 1000;(1000-A1)/2*0.1+67)

When A1 is less then 1000 I get a True in the cell. If it is 1000 or more it is False. What I want is the calculation should be done.