The manager of a store selling tea plans to mix a more expensive tea that cost $7 per pound with a less expensive tea that cost $4 per pound to create a hundred forty pound blend that will sell for $6.10 per pound. how many pounds of each type of tea are required?

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.
 
 They are required:
 expensive tea = 98 pounds
 less expensive tea = 42 pounds