Let the cost of kg of tea =Rs.X
Cost of Kg of sugar =Rs.Y
From the given data
x+y=95 ……………………..(1)
And,
(x−10%x)+(y+20%y)=90
=(x−10100x)+(y+20100y)=90
9x10+6y5=90
9x+12y=900
3x+4y=300 ………………….(2)
Solving (1) and (2) we get
x=80
y=15
Cost of 1kg of Tea =Rs.80