Answer:
30 m
Explanation:
Total length of pipe = 150 m
Central heating system = 20% of 150 m
= 0.2 × 150
= 30 m
Length of pipe remaining = 150 m - 30 m
= 120 m
Bathroom fitting = 25% of 120 m
= 0.25 × 120
= 30 m
The plumber used 30 m of pipe to fit the bathroom