A centrifugal compressor has a constant-width radial diffuser. The diameters at the diffuser inlet and outlet are 0.2 m and 0.3 m, respectively. The flow at the diffuser inlet and outlet is assumed to be steady and uniform. The average velocity at the diffuser inlet and outlet are (60 ê_r + 75 ê_θ) m/s and (u ê_r + 50 ê_θ) m/s, respectively. If the flow through the diffuser is treated as steady and incompressible, the value of u is ________ (rounded off to the nearest integer).