here we take

a+b+c=30k

(a+b+c)^5=30^5k^5

=a ⁵+b+c+5{a⁴(b+c)+a(b+c)⁴+bc⁴+cb⁴}+60{a3(b+c)2...........c2b3}...............(i)

here d terms wid 60 outside bracket r already div by 30..

for d term 5{a⁴(b+c)+a(b+c)⁴+bc⁴+cb⁴}

=5{a(b+c)(a³+(b+c)³)+bc(b³+c³)

=5(a(b+c)(a^3+(30k-a^)3+bc(b^3+c^3)

=in above expression all is div by 30 except, 5bc(b^3+c^3)

aagey................................pata nai............hehehe

if above xpression is div by 30............den its proved..............