=\(5^{20}:\left(5^{15}.6+5^{15}+19\right)\)
=\(5^{20}:[5^{15}\left(6+19\right)\)
=\(5^{20}:[5^{15}.25]\)
=\(5^{20}:5^{15}.5^2\)
=\(5^3\)
520 : ( 515 . 6 + 515 + 19 )
= 520 : [ 515. ( 6 + 9 ) ]
= 520 : [ 515 . 15 ]
= 520 : 515 . 15
= 55 . 15
= 3125 . 15
= 46875