a) $2^{2}$ x 2 - 5 + 12 x $2^{2}$
= $2^{2}$ x ( 12 +2) - 5
= 4 x 14 - 5
= 56 - 5
= 51
b) 2435 + 100 : [ 28 - 2 x $3^{2}$ ]
= 2435 + 100 : [28 - 18]
= 2435 + 100 : 10
= 2435 + 10 = 2445
c) $3^{4}$ x 6 - [ 131 - $6^{2}$ ]
= 243 x 6 - [131 - 36]
= 1458 -95
= 1363
