a) (3 + 6 + 9 + ... + 303) x (245 - 49 x 5)
(3 + 6 + 9 + ... + 303) x (245 - 245)
(3 + 6 + 9 + ... + 303) x 0 = 0
\(\left(3+6+9+...+303\right)\times\left(245-49\times5\right)\)
\(=\left(3+6+9+...+303\right)\times\left(245-245\right)\)
\(=\left(3+6+9+...+303\right)\times0\)
\(=0\)
( 3 + 6 + 9 + .... + 303 ) x ( 245 - 49 x 5 )
= ( 3 + 6 + 9 + .... + 303 ) x ( 245 - 245 )
= ( 3 + 6 + 9 + .... + 303 ) x 0
= 0