Question 309881
let the brother's age be xyears
twice the age = 2x
Kate will be 2x-3 years.
.
Nest year their ages will be 
Brett = x+1
kate = 2x-3  +1
.
x+1 = 3/4 ( 2x-2)
4(x+1) = 3(2x-2)
4x+4=6x-6
2x=10
x=5 Brett's age is 5 years

Kate's age will be x-3 = 5-3 =2 years