The number of $\mathrm{P}-\mathrm{O}-\mathrm{P}$ bonds in cyclictetrametaphoshoric acid $\left(H_4{P}_4{O}_{\mathit{12}}\mathit{\right)}$ which is formed during stepwise hydrolysis of $P_4{O}_{\mathit{10}}$ ?

${\mathrm{P}}_4{\mathrm{O}}_{10}$ aggressively hydrolyzes in water to create orthophosphoric acid.
${\mathrm{P}}_4{\mathrm{O}}_{10} + 6{\mathrm{H}}_2 + 4{\mathrm{H}}_3 = {\mathrm{PO}}_4.$
On the other hand, ${\mathrm{P}}_2{\mathrm{O}}_3$ hydrolysis results in the production of phosphoric acid.

$P_4{O}_6+6H_{2}O\to 4H_{3}P{O}_3$