4(3n+7)=16
12n+28=16
12n=-12
n=-1
Answer:

.
Step-by-step explanation:
5x + 3y = 26 (times 6) 30x + 18y = 156
6x + 7y = 21 (times 5) 30x + 35y = 105
.
30x + 18y = 156
<u>30x + 35y = 105 </u> <u> </u>
-17y = 51

y = -3
.
Substitute the value of y to one of equations
6x + 7y = 21
6x + 7(-3) = 21
6x - 21 = 21
6x = 21 + 21
6x = 42

x = 7
Answer:
12x=10(25+x)
Step-by-step explanation:
Jim's rate=x
Pete's rate=y
Jim and Pete lays the same number of tiles.
So we have,
12x=10y
Pete's can lay 25 more tiles than Jim per hour
We have
y=25+x
Substitute y=25+x into 12x=10y
12x=10y
12x=10(25+x)
12x=250+10x
12x-10x=250
2x=250
x=250/2
=125
x=125
12x=10(25+x) is the equation used to find the rate that Jim can lay tiles
Step-by-step explanation:
so, you got the volume but don't know how to find the surface area ? that is strange for me. what's the problem ?
the surface of a cube or rectangular prism consists of 6 sides that split (for a rectangular prism) into 3 pairs of equal sides :
top and bottom
left and right
front and back
all we need to do is calculate the areas of these 6 rectangles and add them up. that's it.
in our case
top and bottom : 5×4 × 2 = 20×2 = 40 in²
left and right : 4×4 × 2 = 16×2 = 32 in²
front and back : 5×4 × 2 = 40 in²
so, in total, the whole surface area of the prism is
40 + 32 + 40 = 112 in²