Answer: 4 walls
Step-by-step explanation: We know that Ms. O'Grady has approximately 6 1/8 gallons of paint, and needs 1 2/5 gallons per wall she paints. Key words like "per" and "each" tells us that we need to divide these two numbers. However, we run into one problem: the two fractions have 2 different denominators (the number on the bottom of the line) But don't fret! There is an easy fix to this: Multiply the fractions so they match.
In order to do this, we need to find the least common multiple of the numbers 8 and 5. A simple way of doing this is muliplying the numbers together: 8x5=40. Therefore, we need to change our fractions so both denominators equal 40.
1/8 x 5/5 = 5/40
2/5 x 8/8 = 16/40
Now that we have our fractions writen in much simpler terms, we need to add the coefficients to them.
6 + 5/40 = 245/40
1 + 16/40 = 56/40
Now, we divide 245 by 56, which gets us 4 15/40, which can be simplified to 4 3/8. However, Ms. O'Grady can only paint 4 ENTIRE walls. The 3/8 does not matter in this scenario because she can only paint 3/8 of the wall. Therefore, your answer is 4. I hope this helps. :)