Question 955823
Two years ago, John was 3 times as old as Bob. In 5 years time, John will be twice as old as Bob. Find John's present age
J=John; B=Bob
J-2=3(B-2)
J-2=3B-6
J=3B-4
J+5=2(B+5) Substitute for J
3B-4+5=2B+10 Subtract 2B from each side.
B+1=10 Subtract 1 from each side.
B=9 ANSWER 1: Bob is 9 years old.
J=3B-4=3(9)-4=27-4=23 ANSWER 2: John is 23 years old.
CHECK: 
J+5=2(B+5)
23+5=2(9+5)
28=2(14)
28=28