c. 921-[(621-438)x 5 -169 x 4]=
921-(183 x 5 -676)=
921-(915-676)=
921-239=
682
d. {36+[8 x(900-862)]}x 7-148=
[36+(8 x 38)]x7-148=
(36+304)x7-148=
340 x 7-148=
2380-148=
2232
