Question

Solve Q 2,......,10
Pls someone pls

Answer 1

2.
let present age =x
after 12 years=x+12
x+12=3(x-4)
x+12=3x-12
3x-x=12+12
2x=24
x=24/2
x=12years
present age=12years is answer

10.
let denominator =x
numerator =x-5
add 3
denominator =x+3
numerator =x-5+3
numerator =x-2
given
x-2/x+3 =4/5
5(x-2)=4(x+3)
5x-10=4x+12
5x-4x=12+10
x=22
orginal fraction is x-5/x
22-5/22
17/22 is answer

5.
given ratio 8:7
sum=405
8x+7x=405
15x=405
x=405/15
x=27
8x=8(27)
=216
7x=7(27)
=189
216,189 are numbers
6.
present =7x, 5x
10years after
7x+10,5x+10
7x+10/5x+10 =9/7
7(7x+10)=9(5x+10)
49x+70=45x+90
49x-45x=90-70
4x=20
x=20/4
x=5
present ages
7x=7(5)=35years
5x=5(5)=25years
7.
let number be x
double =2x
2x=45+x/2
2x-x/2=45
4x-x/2 =45
3x/2=45
x=2×45/3
x=90/3
x=30 is answer obtained
9.
let number be x
5times=5x
5x-5 =2x+4
5x-2x=4+5
3x=9
x=9/3
x=3 is answer
3.
let cp=x
100%=x
110%=396
110x=396×100
x=396×100/110
x=396×10/11
x=3960/11
x=360
cp=360rs is answer
4.
x+y=4500
10%x=12.5%y
10x=12.5y
x=12.5y/10
x=125y/100
x=5y/4
x+y=4500
5y/4 +y=4500
5y+4y/4 =4500
9y/4=4500
y=4500×4/9
y=500×4
y=2000
x=4500-y
x=4500-2000
x=2500
x=2500,y=2000 is answer
8.
let numbers be 2n, 2n+1
(2n) ^2 -(2n+1)^2 =31
4n^2 -(4n^2+4n+1)=31
4n^2-4n^2-4n-1=31
-4n-1=31
-4n=31+1
-4n=32
n=-32/4
n=-8
numbers are
2n=2(-8)=-16
2n+1 =2(-8)+1
=-16+1
=-15
-16,-15 are numbers