I dont know what to write here, the picture really says all

Explanation:

The front face is a triangle with base b=2 and height h=1.7, so its area is 0.5*b*h = 0.5*2*1.7 = 1.7

The back face is also a triangle with the same area, as it has the same dimensions as the front face. The two triangle areas combine to 1.7+1.7 = 3.4

total base area = 3.4 square cm

The lateral faces are rectangles. The bottom rectangle face is 2 by 3 with area 2*3 = 6. The left rectangle is also 2*3 = 6, as well as the right rectangle face

All three lateral rectangles have the same area. The total lateral surface area is 6+6+6 = 18 square cm

The total surface area is the result of combining the total base area and the lateral surface area

We get the following

total surface area = (total base area)+(lateral surface area) = 3.4+18 = 21.4 square cm.