Question

How do i solve each proportion?

Answer 1

You have to cross multiply (multiply the numerator of the first by the denominator of the second and the numerator of the second by the denominator of the first).

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[19]

$\frac{x+4}{3} = \frac{4}{10}$

$10x+40=12$

$10x = -28$

$x=-2.8$

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[21]

$\frac{4}{n+8} = \frac{10}{8}$

$32 = 8n + 64$

$8n = -32$

$n=-4$

Answer 2

$19) \frac{x + 4}{3} = \frac{4}{10} \\ \\ x + 4 = \frac{4}{10} * 3 \\ \\ x = 1.2 - 4 = -2.8 \\ \\ x = -2.8 \\ \\ \\ 20) \frac{4}{n+8} = \frac{10}{8} \\ \\ 32 = 8n + 64 \\ \\ 8n = 32 -64 = -32 \\ \\ 8n = -32 \\ \\ n = -4$