Ans 1:
Class : Class 7
Equation: ((5(4+n))- 20)/8= 10
= (5(4+n))- 20= 10x8
= 5(4+n)= (10x8)+ 20
=4+n= (10x8+20)/5
=n= ((10x8+20)/5)- 4
=n= (100/5)- 4
=n= 20- 4
n=16
Ans 2:
Class : Class 7
Let the no. Be x
5(4+x)-20/8=10
20+5x-20/8=10
5x/8=10
5x=10×8
5x=80
X=80/5
X=16
According to me.
Ans 3:
Class : Class 8
Let, 3rd no. = x,
Let, 2nd no.= 20/100 (also N1),
Let, 1st no. = 50/100 (also N2),
Then,
Ratio of 1st to 2nd no. = (50/100)/(20/100) =1/2(i.e. 50/100)*5(i.e. 1/{20/100}=100/20}
OR Ratio of 2nd no. to 1st no. =Vice versa of (N1:N2)= 2:5