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:

4y + 228 = 352
4y = 352 - 228
4y = 124
--- ----
4 4
------------
| y = 31 |
------------
hope this helps
N+1-3n=5+n+1-2
Simplify it
-2n+1 = n+4
Add 2n to both sides
1 = 3n+4
Subtract 4 from both sides
-3 = 3n
Divide by 3
n = -1
You have an angle of elevation of 3 degrees and you're 2000 ft from base of 30 story building.
<span>Draw a picture of this. Then tan(3) = ht of bldg/2000 </span>
<span>I get a height of 104.82 ft rounded to 2 dp. </span>
<span>5. Ok. use the Pythagorean Theorem here to find the hypotenuse of the right triangle </span>
<span>hypt = sqrt(50^2 + 9^2) </span>
<span>Now sine of the angle of elevation is 50/hypt. = 0.984 or 0.98 to 2 dp.</span>
So percent means parts out of 100 so 17%=17/100
400 marbles
17% of 400=blue
<span>'of' can be translated to multiply </span>
17%=17/100
17/100 ties 400=6800/100=68
<span>he has 68 blue marbles.</span>