We have two right triangles and three different rectangles.
The formula of an area of a right triangle:

l₁, l₂ - legs
We have l₁ = 20cm and l₂ = 21cm. Substitute:

The formula of an area of a rectangle:

l - length
w - width
We have:
rectangle #1: l = 22cm, w = 29cm

rectangle #2: l = 22cm, w = 21cm

rectangle #3: l = 22cm, w = 20cm

The total Surface Area of the triangular prism:

He is incorrect because he multiplied the bases.
Answer:
option 2
Step-by-step explanation:
Answer:
x=30
Step-by-step explanation:
that's a 90º angle so 90÷3=30
Answer: $2.55
Step-by-step explanation:
He bought the second shirt for half off the first shirt's price. He therefore bought it at:
= 19.99/2
= $10.00
Total paid for both shirts is therefore:
= 19.99 + 10
= $29.99
Sales tax is 8.5% so he paid:
= 29.99 * 8.5%
= 2.54915
= $2.55