Let x = Ricardo's age now
x + 4 = Miriam's age now
x - 10 = Ricardo's age 10 years ago
x + 4 - 10 = x - 6 = Miriam's age 10 years ago
Miriam's age 10 years ago=3(Ricardo's age 10 years ago)
So, x - 6 = 3(x - 10)
x - 6 = 3x - 30
-2x = -24
x = 12
Answer: Ricardo is 12 years old and Miriam is 16 years old.