Answer:
Total surface area
1) 46cm²
4) 304cm²
Explanation:
1) First you need to work out each face on its own, opposites will be the same such as the front and back, top and bottom, side to side, because its a rectangle.
Formula : Base x height
Front/back : 5x3=15 and 15 =30 (added together)
top/bottom : 1x5= 5 and 5 = 10
side/side : 3x1= 3 and 3 = 6
30+10+6=46cm²
4) lets work out the easy ones first using the same formula from question 1 for one surface area but this is a trapezium, which is a irregular quadratical shape so the sides would most liky be different from each other except the front and back.
Top : 5x8=40
bottom : 3x10=30
right side : 12x8=96
Left side : 12x10=120
front/back= 12x3=36 / 2 = 18
Because if u added another side to make it a rectangle then divide by 2 would get the answer or 1/2 x base x height also works.
40+30+96+120+18=304cm²