1) Answers: Bobby = 22, Chris = 19
Explanation:
          This year     Last year
Bobby:    3 + x        3 + x - 1  = 2 + x
 Chris:     x            x - 1
Bobby (last year) + Chris (last year) = sum (last year)
    2 + x       +      x - 1       =    39
2 + x + x - 1 = 39
2 + 2x - 1 = 39
2x + 1 = 39
2x = 38
x = 19
Bobby (this year): 3 + x  = 3 + 19  = 22
Chris (this year): Â x = 19
2. Answers: Beth = 25, Celeste = 30
Explanation:
         This year      Next year
Beth: Â Â Â Â Â Â x - 5 Â Â Â Â Â Â Â x - 5 + 1 Â = x - 4
Celeste:      x             x + 1
Beth (next year) + Celeste (next year) = sum (next year)
     x - 4      +      x + 1        =   57
x - 4 + x + 1 = 57
2x - 3 = 57
2x = 60
x = 30
Beth (this year): x - 5 Â = 30 - 5 Â = 25
Celeste: x = 30
3. Answers: Donna = 38, brother = 50
Explanation:
         This year       in 2 years
Donna:     x - 12          x - 12 + 2    and    (x + 2)/2 + 14
brother:      x              x + 2
Donna (in 2 years) = Donna (in 2 years)
    x - 10      =     (x+2)/2 + 14
x - 24 = (x+2)/2
2x - 48 = x + 2
x = 50
Donna (this year): x - 12 Â Â = 50 - 12 Â = 38
brother: x = 50
4. Answers: Freddie = 40, Elena = 8
Explanation:
         This year       in 4 years
Freddie:      5x           5x + 4    and    3(x + 4) + 8
Elena:        x            x + 4
Freddie (in 4 years) = Freddie (in 4 years)
     5x + 4       =     3(x + 4) + 8 Â
5x + 4 = 3x + 12 + 8
2x = 16
x = 8
Freddie: 5x  = 5(8)  = 40
Elena: x  = 8