VARIABLES
M=50 amount of tea mixture
T=111 cost of the mixture in Rs per kilogram
H=3 price of the more expensive tea
L=1.5 price of the cheaper tea
x unknown amount of the cheaper tea
y unknown amount of the higher priced tea
A starting system of equations for the description
What you want to do is to solve for x and y.
A lesson on such a two-part mixture problem , https://www.algebra.com/my/mixture-price-two-part-both-parts-unknown.lesson?content_action=show_dev