Question 234276
John's age now=3x/4
Sally's age now=x
In 5 years John will be 3x/4+5
Sally will be 4/5(x+5)
3x/4+5=4/5(x+5)
3x/4+5=(4x+20)/5
(3x+4*5)/4=(4x+20)/5 crosss multiply.
5(3x+20)=4(4x+20)
15x+100=16x+80
15x-16x=80-100
-x=-20
x=20 ans. for sally's age now.
3/4*20=60/4=15 ans. for John's age now.
Proof:
3/4*20+5=4/5(20+5)
15+5=4/5*25
20=100/5
20=20