Question

If 2:5=x:20 then x=?

a)50 b)2 c)1/2 d)8

Answer 1

Given:

`2:5 = x:20`

We know that:

• Since the LHS and the RHS are equal, they form a proportion
• 
  `\text{a:b} = \text{c:d} \rightarrow \text{ad} = \text{bc}`

To find x, let's multiply the extremes and put the product on one side. Then multiply the middles and put the product on the other side.

• ⇒
  `2:5 = x:20`
• ⇒
  `2 * 20= x * 5`

Now, solve for x.

• ⇒
  `2 * 20= x * 5`
• ⇒
  `40 = 5x`
• ⇒
  `(40)/(5) = (5x)/(5)`
• ⇒
  `\boxed{x = 8}`

Answer 2

x = 8

Explanation:

Write as fraction form

`(2)/(5)=(x)/(20)`

`\mathrm{Switch\:sides}`

`(x)/(20)=(2)/(5)`

`\mathrm{Multiply\:both\:sides\:by\:}10`

`(x)/(20)\cdot \:10=(2)/(5)\cdot \:10`

`\mathrm{Simplify}`

`(x)/(2)=4`

`\mathrm{Multiply\:both\:sides\:by\:}2`

`(2x)/(2)=4\cdot \:2`

`\mathrm{Simplify}`

`x=8`

Hence, Answer is [D} x = 8

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