The cost of making a dress is partly varies with the amount of time it takes to make the dress. If the dress takes 3 hours to make, it costs #2700. If it takes 5 hours to make the dress, it costs #3100. Find the cost if it takes 1 1^2 hours to make the dress.
k + 3 h = 2700
k + 5 h = 3100
subtracting equations ... 2 h = 400 ... h = 200 ... k = 2100
1 1/2 h + k = ?