150 times (X-5)= 120x.

150x-750= 120x

150 x-750+750 = 120 x+750

150x= 120x+750

150 x- 120 x = 120 x+750- 120 x

30x=750

30x divided by 30=750 divided by 30

x=25

120 times 25=3000 (sets) A: There are 3000 sets of clothes in this batch.