Question 171434
Let x=Jackie's brother's age now; in 4 years he will be x+4 years old
Then x+5=Jackie's age now;  in 4 years she will be x+5+4=x+9 years old

Now we are told that:
x+9=2(x+4)  get rid of parens (distributive)
x+9=2x+8  subtract x and also 8 from each side
x-x+9-8=2x-x+8-8  collect like terms
1=x or
x=1---------------------Jackie's brother's age now
x+5=1+5=6----------------Jackie's age now
CK
6+4=2*(1+4)
10=10

Hope this helps----ptaylor