T: Price of 1 kg tea
S: Price of 1 kg sugar
4S: Price of 4 kg of sugar

T+4S = 35 — Eqn. A
T = 35 -4S

1.1T: Price of 1 kg tea after 10% increase
1.5S: Price of 1 kg sugar after 50% increase

1.1T + 4(1.5S) = 42.5
1.1T + 6S = 42.5 — Eqn.B

**Solve simultaneously Eqns. A and B

1.1(35-4S) + 6S = 42.5
38.5 -4.4S + 6S = 42.5
1.6S = 4
S = 4/1.6= 2.5

Old Price of 1 kg Sugar = 2.5
New Price of 1 kg Sugar = 2.5*1.5 = 3.75