31*63-31*13= 31(63-13) = 31*50=31*100/2 = 3100/2 = 1550
31· 63 - 31· 13 =
= 31· (63 - 13) =
= 31 · 50 = 1550
31*63-31*13= 31(63-13) = 31*50=31*100/2 = 3100/2 = 1550
31· 63 - 31· 13 =
= 31· (63 - 13) =
= 31 · 50 = 1550