What is the surface area of this triangular prism rounded to the nearest tenth 3.6 km 8.5 km 7.7 km 1.8 km

The picture in the attached figure

we know that
[surface area]=2*[area of the base]+[perimeter of the base]*height
area of the base=3.6*7.7/2----> 13.86 Km²
perimeter of the base=3.6+7.7+8.5-----> 19.8 Km
height=1.8 Km

[surface area]=2*[13.86]+[19.8]*1.8-------> 63.36 Km²-----> 63.4 Km²

the answer is 
63.4 Km²

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.