The original playground area is 50m×30m= 1500m3, and it is 1500+600=2 100m3 after expansion.

The expanded width is 2100 ÷ 50+10 = 2100 ÷ 60 = 35m, so the width is increased by 35-30=5m.

The width increases by x, which is derived from the meaning of the question, (50+10) × (30+x) =1500+600.

So 30+x=2 100/60, so x=35-30=5.