On the first year, two cows produced 8100 liters of milk. On the second year, their production increased by 15% and 10% respectively, and the total amount of milk increased to 9100 liters a year. How many liters of milk from each cow in each year?

**Answer:**

**Step-by-step explanation:**

Let:

x = liters of milk produced by the first cow

y = liters of milk produced by the second cow

let’s convert percentage values to decimal

10% = 0.1

15% = 0.15

Solution:

On the first year,

x + y = 8100 <=== equation 1

On the second year

(x + 0.1x) + ( y + 0.15y) = 9100

1.1x + 1.15y = 9100 <=== equation 2

Two equations and two unknowns. Solving for x and y using substitution method;

from equation 1

x + y = 8100

y = 8100 -x <=== equation 3

susbstitute equation 3 in equation 2

1.1x + 1.15y = 9100

1.1x + 1.15(8100 – x) = 9100

1.1x + 1.15(8100) – 1.15x = 9100

-0.05x + 9315 = 9100

0.05x = 215

x = 215/0.05

**x = 4300 answer**

y = 8100 – x = 8100 – 4300 = **3800 answer**