b. After a 25% discount, the price of a T-shirt was $12. What was the price beforethe discount?c. Compared to last year, the population of Boom Town has increased by 25%. Thepopulation is now 6,600. What was the population last year?**Key Takeaway:

The price before  the discount is $ 16The population last year is 5280Solution: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 = $12Let the original price be "a"[tex]\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}[/tex]Thus the original price is $ 16C) 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.[tex]\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}[/tex]Thus the last year population is 5280