help me with this please

Step-by-step explanation:
the scale factor is 1 : 150
you don't know what that means ?
it means that every unit (here cm) in the diagram corresponds in reality to 150 units.
so, 1 cm in the diagram is 150 cm in reality.
therefore we only need to multiply the sizes in the diagram by 150, and we get the real sizes.
length : 5 × 150 = 750 cm (7.5 m)
breadth : 3 × 150 = 450 cm (4.5 m)
and the perimeter is as for every rectangle :
2×length + 2×breadth = 2×750 + 2×450 = 1500 + 900 =
= 2400 cm (24 m)