Four friends have different numbers of cows on their farms. Jorge has 3 times as many cows as Carla. Marcus has half as many cows as Jorge. Dominique has 2 less than 4 times as many cows as Carla. How many cows do they each have if they have a total of 169 cows?

Let us say:

x = Jorge

y = Carla

z = Marcus

a = Dominique

We are given that:

x = 3y - - > 1

z = 0.5x - - > 2

a = 4y - 2 - - > 3

x + y + z + a = 169 - - > 4

Substituting 1 to 2:

z = 0.5 (3y) = 1.5y - - > 5

Substituting 1, 3 and 5 to 4:

3y + y + 4y - 2 + 1.5y = 169

9.5y = 171

y = 18

Hence,

x = 3y = 3*18 = 54

z = 0.5x = 0.5 (54) = 27

a = 4y - 2 = 4 (18) - 2 = 70

y = 18