Question

Find the value of x in the following proportion
(a) 3:7::x:21 (b) x:45 :: 4:36​

Answer 1

Answer : a}X=9. b)x=5

Answer 2

Step-by-step explanation:

$(a) 3 : 7 : : x : 21 \\ \therefore \: \frac{3}{7} = \frac{x}{21} \\ \therefore \: 7 \times x = 3 \times 21 \\ \therefore \: x = \frac{3 \times 21}{7} \\ \therefore \: x = 3 \times 3 \\ \huge \fbox{ \therefore \: x = 9} \\ \\ (b) x : 45 : : 4 : 36 \\ \therefore \: \frac{x}{45} = \frac{4}{36} \\ \therefore \: x \times 36 = 4 \times 45 \\ \therefore \: x = \frac{4 \times 45}{36} \\ \therefore \: x = \frac{ 45}{9} \\ \therefore \: x = 5\\ \huge \fbox{ \therefore \: x = 5}$