Percentage relations between x and y.(Relation between two variables)

Question

I would like to know easiest method to solve following:

Que 1:

If 10% of x=y, then y% of 30 is same as what % of x?

My Approach:

Step 1: (10 * x)/100 = (10 * y)/100

Step 2: (30 * y)/100 = (3 * y)/10

Don't know further.

 

Que 2:

What percentage of numberes from 1 to 89 are divisible by 5?

My Approach:

Step 1: Total numberes divisible by 5 from 1-89 = 17

Step 2: Considering 90 as 100%

Step 3: So 17 is what % of that

Which i solve like

(17 * 100)/90 = 18.888%

I get ans: 18.8888%, but i think i am wrong, help here.

Thank You!

Answer 1

For question $1$, you have: $\dfrac{x}{10} = y \Rightarrow \dfrac{y}{100}\cdot 30 = \dfrac{k}{100}\cdot x=\dfrac{k}{100}\cdot 10y\Rightarrow k = ?$

For question $2$, you have $17$ numbers that are multiple of $5$ out of $89$ numbers. Thus the percentage is $\dfrac{17}{89}\cdot 100\text{%} \approx 19 \text{%}$

Answer 2

For the 1st one: $10\%$ of $x=y$, then $y\%$ of $30$ is same as what $\%$ of $x$?

Consider "of" as multiplication, so $10/100=1/10=y\%$

Now $y\%$ of $30$ means, $1/10*30=3$. So the answer is $3$.