Question

please help in this question ​

Answer 1

Answer:

sum of 7 years - sum of 2 years =P+intrest for  7 years - P+interest for 2 years therefore

intrerest for 5 years is 1230-780=450

interest for 1 year=450/5=90

since its for 5 years

interest for 2 year=90*2=180

principal=sum of money-interest

principal=780-180=600

now by using si of 1 year

SI= p*r*t/100

90=600*r*1/100

r=15%

Step-by-step explanation:

Answer 2

Amount of 2 nd years=₹780

Amount of 7 th years=₹1230

Then interest Amount of 5 years

1230-780

=₹450

Then Interest in one Year

=450/5

=₹90

Amount in 2nd Year=90×2=₹780

SI in 2nd Year=₹180

Then Principal=780-180

=₹600

Given

Principal=₹600

Time=2 years

Rate=r

SI=₹180

$\frac{principal \times time \times rate}{100} = si \\ \\ \frac{600 \times 2 \times r}{100} = 180 \\ \\ r = 180 \times \frac{100}{600 \times 2} \\ r = 15\%$

Rate=15%

Now We get

Rate=15%

Principal=₹600