Answer: He plans to buy 28 tiles.
Explanation:
Given: Dimensions of floor = 6-by-5 feet
Since area of rectangle = length x width
Then , area of floor = 6 x 5 square feet = 30 square feet
Dimension for vanity 2-by-2.5-feet , area of vanity = 2 x 2.5 sq. feet = 5 sq. feet
Area of floor for tiling = 30 square feet - 5 sq. feet
= 25 square feet
Area of 1 tile = 1 x 1 = 1 square feet
Number of tiles required to cover 25 sq. feet = 25÷1=25
10 percent extra = 10% of 25+25 = 2.5+25=27.5 ≈28
Hence, he plans to buy 28 tiles.