To simplify this equation, we will first distribute the numbers outside the parentheses to the terms inside the parentheses:

3·4·(2·5к + 3) + 4·(2 - 2·7к) = 1,4 - 1,5к
12·(10к + 3) + 4·(2 - 14к) = 1,4 - 1,5к

Next, let's simplify the terms inside the parentheses to get:

120к + 36 + 8 - 56к = 1,4 - 1,5к

Combining like terms, we get:

64к + 44 = 1,4 - 1,5к

Now, let's isolate the variable 'к' on one side of the equation.

Adding 1,5к to both sides:

64к + 1,5к + 44 = 1,4

Combining like terms:

65,5к + 44 = 1,4

Subtracting 44 from both sides:

65,5к = 1,4 - 44
65,5к = 42

Now, we will divide by 65,5 on both sides to solve for 'к':

к = 42 / 65,5
к = 0,6423

Therefore, the solution to the equation is к = 0,6423.