[tex] \frac{1}{5} \times 100 = 20 [/tex]
[tex] \frac{1}{5} \times 105 = 21[/tex]
[tex] \frac{1}{5} \times 110 = 22[/tex]
[tex] \frac{2}{3} \times 624 \\ 2 \times 208 = 416[/tex]
[tex] \frac{2}{3} \times 1248 \\ 2 \times416 = 832[/tex]
[tex] \frac{2}{3} \times 2496 \\ 2 \times 832 = 1664[/tex]
[tex] \frac{3}{7} \times 840 \\ 3 \times 120 = 360 [/tex]
[tex] \frac{4}{7} \times 840 \\ 4 \times 120 = 480[/tex]
[tex] \frac{5}{7} \times 840 \\ 5 \times 120 = 600 [/tex]