9. Quyidagi chizmaga ko‘ra uchta taxtaning uzunligining yig‘indisi necha metrga teng?

Birinchi taxta 3 m 50 cm. Ikkinchi taxta undan 1 m 80 cm qisqa: 3 m 50 cm − 1 m 80 cm = 1 m 70 cm. Uchinchi taxta birinchisidan 80 cm uzun: 3 m 50 cm + 80 cm = 4 m 30 cm.

Yig‘indi: 3 m 50 cm + 1 m 70 cm + 4 m 30 cm = 9 m 50 cm.

Javob: 9 m 50 cm (C).