tolong ka dibantu please

[tex]6. \\ \frac{12 \times 7}{2} = 42 \\ 7. \\ 189 = \frac{a \times 21}{2} \\ 378 = a \times 21 \\ a = 18 \\ 8. \\ 88 = \frac{a \times 11}{2} \\ 176 = a \times 11 \\ a = 16 \\ 9. \\ 34 = \frac{17 \times t}{2} \\ 68 = 17 \times t \\ t = 4 \\ 10. \\ 625 = \frac{50 \times t}{2} \\ 1250 = 50 \times t \\ t = 25[/tex]

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