упростите выражение 7 3/8-b+4 7/15 +b-7 3/8-2 4/5 срочно!!!

= 4 7/15 - 2 4/5 = 4 56/120 - 7 45/120  = 536/120 - 885/120 = 536/120 + (-885/120) = - (885/120 - 536/120) = -349/120 = -2 109/120