We define the variables of the problem:
x = expensive tea
y = less expensive tea
We write the system of equations:
7x + 4y = 6.10 * (140) = 854
x + y = 140
The system of equations is:
7x + 4y = 854
x + y = 140
Resolving we have:
x = 98
y = 42
Note: see attached image for the solution.
Answer:
They are required:
expensive tea = 98 pounds
less expensive tea = 42 pounds