plisss jawab yang dilingkari nomer 11

(1/2 × 22/7 × 10.5 × 10.5= 11 × 1.5 × 10.5= 173.25=173/4) + (1/2 × 21 ×30= 21×15= 315) = 137 1/4 + 315=488 1/4