A soap bubble of surface tension \( 0.04 \, \text{N/m} \) is blown to a diameter of \( 7 \, \text{cm} \). If \( (15000 - x) \, \mu \text{J} \) of work is done in blowing it further to make its diameter \( 14 \, \text{cm} \), then the value of \( x \) is ____________ . \( \left( \pi = \dfrac{22}{7} \right) \).
