$(1)A_s=5-D32,A_s^{\text{'}}=2-D25,d^{\text{'}}=60mm$

$(2)A_s=5-D32,A_s^{\text{'}}=2-D29,d^{\text{'}}=50mm$

$(3)A_s=3-D35,A_s^{\text{'}}=2-D25,d^{\text{'}}=60mm$

Fig. $1$Calculate the design bending strength for the following three reinforcing bar arrangement cases for the rectangular cross$-$section of the double reinforcing bar in Figure $1.$ Here, the amount of tension reinforcement As is the cross$-$sectional area including the amount of compression reinforcement As$\text{'}.($fck$=28$MPa, fy$=400$MPa$)$