Question 1013490
Let the youngest child be x.  The next kids are y and z.  We have
x + y + z = 50
x = (1/2)z  or z = 2x
z-10 = 7(x-10)
Substituting we have
2x - 10 = 7(x - 10)
2x - 10 = 7x - 70
5x = 60
x = 12 (youngest)
z = 2(12) = 24 (oldest)
y = 50 - 12 - 24 = 14 (middle)