A fluid moves in a steady flow manner between two sections in a flow line. At section $1$: $A_1=$

$10f{t}^2,U=100fpm,v_1=4f\frac{t^3}{l}b{b}_m$

At section $2$: $A_2=2f{t}^2,{}_2=0\mathrm{.}20lb\frac{b_m}{f}{t}^3,U_2=120fpm.$ Calculate $($a$)$ the mass flow rate, and the

$($b$)$ change of mass stored in system $m.$