Question
If a : b = c : d, prove that: 5a + 7b : 5a – 7b = 5c + 7d : 5c – 7d.

Answer

Given $\frac{a}{b}=\frac{c}{d}$
$\Rightarrow \frac{5 a}{7 b}=\frac{5 c}{7 d}$ (Multiplying each side by 5/7)
$\Rightarrow \frac{5 a+7 b}{5 a-7 b}=\frac{5 c+7 d}{5 c-7 d}$ (By componendo and dividendo)

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free