Number of $s{p}^3$ hybridised boron in borax is .

The number of $s{p}^3$ hybridised boron atoms in borax are

In the tetranuclear unit of borax $\left[B_4{O}_5\right(OH{)}_4{]}^{2-}$, the number of B – O – B bridges formed between $s{p}^3$ boron & $s{p}^2$ boron is ‘x’ and the number B-O-B bridges formed between $s{p}^3$ boron & $s{p}^3$ boron is ‘y’.
Then (x – y) is___

The number of $s{p}^2$ hybridised boron atoms in borax are