Hey there!
There are 1000 mL in a liter.
1.4 L + 0.045 L = 1.445 L
In total there is 1.445 L of the solution.
To find the percent of isopropyl alcohol, divide the amount of isopropyl alcohol by the total amount.
0.045 รท 1.445 = 0.0311
Convert to a percent.
3.11%
Hope this helps!