Bài 8A : Thực hiện phép tính ( tính hợp lí nếu có thể )
a/ 72.121+27.121+121
b/100 + 97 + 94 + ..... + 4 +1
Bài 10A : Tìm x biết
a/ ( x - 29 ) - 11 = 0
b/ ( x + 5 ) : 3 - 11 = 4
c/ 231 + ( 312 - 2x ) = 531
Bài 10B : Tìm x biết 
a/ ( 50 - x ) + 12 = 31
b/ 75 : ( x - 2 ) + 4 = 7
c/ 125 - 3 ( x + 3 ) = 65 
\xmlClass{guppy_elt guppy_loc_m_e1_0}{2}\xmlClass{guppy_elt guppy_loc_m_e1_1}{7}\xmlClass{guppy_elt guppy_loc_m_e1_2}{2}\xmlClass{guppy_elt guppy_loc_m_e1_3}{4}\xmlClass{guppy_elt guppy_loc_m_e1_4}{-} ( \xmlClass{guppy_elt guppy_loc_m_e2_0}{2} ^{3} \xmlClass{guppy_elt guppy_loc_m_e3_0}{.}\xmlClass{guppy_elt guppy_loc_m_e3_1}{3} ^{2} \xmlClass{guppy_elt guppy_loc_m_e4_0}{-}\xmlClass{guppy_elt guppy_loc_m_e4_1}{2} ^{ \xmlClass{guppy_elt guppy_loc_m_f4_c1_e1_0}{4} } \xmlClass{guppy_elt guppy_loc_m_e5_0}{.}\red{\xmlClass{main_cursor}{\xmlClass{cursor}{\hspace{0pt}}}}\xmlClass{guppy_elt guppy_loc_m_e5_1}{3} ) \phantom{\xmlClass{guppy_elt guppy_blank guppy_loc_m_e6_0}{\hspace{\xmlClass{guppy_elt guppy_loc_m_e1_0}{2}\xmlClass{guppy_elt guppy_loc_m_e1_1}{7}\xmlClass{guppy_elt guppy_loc_m_e1_2}{2}\xmlClass{guppy_elt guppy_loc_m_e1_3}{4}\xmlClass{guppy_elt guppy_loc_m_e1_4}{-} ( \xmlClass{guppy_elt guppy_loc_m_e2_0}{2} ^{3} \xmlClass{guppy_elt guppy_loc_m_e3_0}{.}\xmlClass{guppy_elt guppy_loc_m_e3_1}{3} ^{2} \xmlClass{guppy_elt guppy_loc_m_e4_0}{-}\xmlClass{guppy_elt guppy_loc_m_e4_1}{2} ^{ \xmlClass{guppy_elt guppy_loc_m_f4_c1_e1_0}{4} } \xmlClass{guppy_elt guppy_loc_m_e5_0}{.}\red{\xmlClass{main_cursor}{\xmlClass{cursor}{\hspace{0pt}}}}\xmlClass{guppy_elt guppy_loc_m_e5_1}{3} ) \phantom{\xmlClass{guppy_elt guppy_blank guppy_loc_m_e6_0}{\hspa