At the time a buyer was ordering his goods, tea was quoted at 1.20 dollars per lb. and coffee at 4 dollars per lb. He decided to buy a certain amount of each. In all, 104 lb. were bought, at a total cost of $248. How much of each commodity did he buy? Use only one variable.
Let's see...if $x$ is the number of pounds of tea, then $104 - x$ is the number of pounds of coffee. That means he spent \$1.2$x$ dollars on tea and\$ $4(104-x)$ dollars on coffee.
Let $x$ be the number of pounds of tea bought.
Then the number of pounds of coffee bought must be $104 - x$.
The cost of the tea is $1.2x$ and the cost of the coffee is $4(104-x)$.
Can you create an equation for the total cost? If so, then solve it to find the number of pounds of tea.