e without using calculators the foll \( \frac{1}{7} \) of \( 49+4-\frac{1}{5}(15-20) \) \( 8 \times-5+3 \)

83 Найдите произведение: \( \begin{array}{l}\text { а) } \frac{4}{9} \cdot \frac{9}{7} \cdot \frac{7}{17} \cdot \frac{17}{28} ;\end{array} \)

c) \( \frac{5}{6}-\frac{7}{8}+\frac{11}{12} \)

A ladder has 50 rungs. The bottom rung is 1 m long. Each rung is \( 12,5 \mathrm{~mm} \) shorter than the rung beneath it. Determine the total length of wood required to make 50 rungs.

3. (a5-g18-14) Ko'p qavatli uyning 4 - qavatigacha bo'lgan masofa 12 metr. Shu uyning 12 -qavatigacha bo'lgan masofa necha metr? \( \begin{array}{llll}\text { A) } 48 & \text { B) } 44 & \text { C) } 36 & \text { D) } 33\end{array} \)

Exercise 4.1 1 Work out the highest common factor (HCF) of \( \begin{array}{ll}\text { a } 8 \text { and } 12 & \text { b } 6 \text { and } 15 \\ \text { c } 7 \text { and } 35 & \text { d } 24 \text { and } 40\end{array} \) \( \begin{array}{l}2 \text { Which fraction is larger in each pair? }\end{array} \)