Aprism 2m tall. the base is a trapezoid whose parallel sides are 7m and 3m. the other sides are each 4m. the altitude of the trapezoid measures 3.5m. find the surface area and round it to the nearest tenth, if necessary.

To solve this we are going to use the formula for the total surface area of a trapezoidal prism: 
where
is the total surface area of the trapezoidal prism
is the lateral surface area of the trapezoidal prism 
is the Area of base (area of the trapezoid)

To find , we are going to use the formula for the lateral surface area of a trapezoid: 
where 
is the larger base of the trapezoid 
is the shorter base of the trapezoid 
and  are the other sides of the trapezoid
Remember that the parallel sides of a trapezoid are its bases, so: and . We also know that the other sides are each 4m, so:  and . Also, since the prism is 2m tall, .  Lets replace those values in our formula to find :





Now, to find the area of the base, we are going to use the formula for the area of a trapezoid: 
where
is the area of the trapezoid
is the altitude of the trapezoid 
is the larger base of the trapezoid 
is the shorter base of the trapezoid 
We know for our problem that , , and . Lets replace those values in our formula to find :






Now that we have  and , we can finally use the formula for the total surface area of a trapezoidal prism:





We can conclude that the surface area of the prism is 71 square meters.

Could you make it more clear?