1)Calculate the product:
21a + 10a - 3a
2)Collect like terms:
28a
Answer:
28a
Surface area of the cylinder = 816.4 sq. ft.
Solution:
Height of the cylinder = 21 ft
Diameter of the cylinder = 10 ft
Radius of the cylinder = 10 ÷ 2 = 5 ft
Use the value of
= 3.14
Surface area of the cylinder = 
Substitute the given values in the surface area formula, we get
Surface area of the cylinder 

ft²
Hence the surface area of the cylinder is 816.4 sq. ft.
The first would be “6x squared” and the 2nd term would be “5xy”