let 'x' be the amount of coffee which costs 190/kg
'y' be the amount of coffee which costs 275/kg
since you know that 1 kg is 225 then you'll the equations as:
(since the mix is 1 kg then you will have the idea that x + y =1)
x + y = 1 ----equation 1
(since you have the cost and the price you can have the second equation)
190x +275y = 225 ---equation 2
rearranging equation 1
x + y = 1
x = 1 - y ----equation 3
substitute equation 3 to equation 2
190x + 275y = 225
190(1-y) + 275y = 225
190 - 190y + 275y = 225
85y = 225 -190
85y = 35
y = 7/17 kg
substitute to equation 3
x = 1 - 7/17
x = 10/17 kg