Remus bought a mug and 4 towels for $13. Joanne bought a mug and 7 towels for $19. Find the cost of the mug.
The difference in total cost is the cost of the extra towels.
Let's put this into equations,
\(m + 4t = 13\)
\(m + 7t = 19\)
Subtracting the equations we get,
\(3t = 6\)
\(t = 2\)
Now we know the cost of a towel, we can plug it back into one of the equations.
\(m + 8 = 13\)
\(m = 5\)
So a mug costs 5 dollars.