A beam with rectangular cross section of size $250mm$ wide and $350mm$ deep is prestressed by a force of $400kN$ using $8$ numbers of $7mmf$ steel cables located at an eccentricity of $75mm.$ Determine the loss of prestress due to creep of concrete. Grade of concrete is M$40$; Co$-$efficient of creep is $2$; stress at transfer is $80\%,$ Modulus of elasticity of steel$(($:$E_s\}$ is $2\mathrm{.}0{10}^5$MPa.