a)
683 x 35 = 23905
1954 x 425 = 830450
2438 x 306 = 746028
b\(\frac{7}{9}\) x \(\frac{3}{35}\) = \(\frac{7 \times 3}{9 \times 35}\) = \(\frac{7 \times 3}{3 \times 3 \times 5 \times 7}\) = \(\frac{1}{3 \times 5}\) = \(\frac{1}{15}\)
\(\frac{9}{22}\) x 55 = \(\frac{9 \times 55}{22}\) = \(\frac{9 \times 5 \times 11}{2 \times 11}\) = \(\frac{9 \times 5}{2}\) = \(\frac{45}{2}\)
\(\frac{11}{17}\) : \(\frac{33}{34}\) = \(\frac{11}{17}\) x \(\frac{34}{33}\) = \(\frac{11 \times 34}{17 \times 33}\) = \(\frac{11 \times 2 \times 17}{17 \times 3 \times 11}\) = \(\frac{2}{3}\)
d)