Question

B. After a 25% discount, the price of a T-shirt was $12. What was the price before

Answer 1

The price before  the discount is $ 16

The population last year is 5280

Solution:

B) After a 25% discount, the price of a T-shirt was $12. What was the price before  the discount?

Given that after a 25% discount, the price of a T-shirt was $12.  

We have to find what was the price before the discount?  

Now, we know that,

original price – discount = selling price

Original price – 25% of original price = $12

Let the original price be "a"

$\begin{array}{l}{\mathrm{a}-25 \% \text { of } \mathrm{a}=12} \\\\ {a-\frac{25}{100} \times a=12} \\\\ {a\left(1-\frac{25}{100}\right)=12} \\\\ {a\left(1-\frac{1}{4}\right)=12} \\\\ {a\left(1-\frac{1}{4}\right)=12} \\\\ {a\left(\frac{3}{4}\right)=12} \\\\ {a=12 \times \frac{4}{3}=16}\end{array}$

Thus the original price is $ 16

C) Compared to last year, the population of Boom Town has increased by 25%. The  population is now 6,600. What was the population last year?

Last year population + 25% of last year population = present population.

$\begin{array}{l}{ \text { Last year population( }100 \%+25 \%)=6600} \\\\ {\text { Last year population } \times 125 \%=6600} \\\\ {\text { Last year population } \frac{125}{100}=6600} \\\\ {\text { Last year population }=6600 \times \frac{4}{5}} \\\\ {\text { Last year population }=660 \times 2 \times 4} \\\\ {\text { Last year population }=5280}\end{array}$

Thus the last year population is 5280