7 4/5 = 7 36/45
8 8/9 = 8 40/45
+----------
15 75/45
15 75/45 = 16 30/45
surface area (S) of a right rectangular solid is:
S = 2*L*W + 2*L*H + 2*W*H (equation 1)
where:
L = length
W = width
H = height
-----
you have:
L = 7
W = a
H = 4
-----
formula becomes:
S = 2*7*a + 2*7*4 + 2*a*4
simplify:
S = 14*a + 56 + 8*a
combine like terms:
S = 22*a + 56
-----
answer is:
S = 22*a + 56 (equation 2)
-----
to prove, substitute any value for a in equation 2:
let a = 15
S = 22*a + 56 (equation 2)
S = 22*15 + 56
S = 330 + 56
S = 386
-----
since a = 15, then W = 15 because W = a
go back to equation 1 and substitute 15 for W:
S = 2*L*W + 2*L*H + 2*W*H (equation 1)
where:
L = length
W = width
H = height
-----
you have:
L = 7
W = 15
H = 4
-----
equation 1 becomes:
S = 2*7*15 + 2*7*4 + 2*15*4
perform indicated operations:
S = 210 + 56 + 120
S = 386
-----
surface area is the same using both equations so:
equations are good.
formula for surface area of right rectangle in terms of a is:
S = 22*a + 56
-----
Answer:
Addition Property of Equality.
Inverse property of multiplication.
Step-by-step explanation:
Given the equation:
First of all, let us use Addition Property of Equality.
According to the property, if we add a number on both sides of an equality, there is no change in the equality.
In other words, the equality will be same if we add the same number on Left Hand Side and Right Hand Side of the equality.
First of all, let us add 15 on both sides of the equality:
Now, let us Inverse property of multiplication.
i.e. Multiplication of a number with its inverse is equal to 1.
So, let us multiply the given equation with 
The properties used are:
Addition Property of Equality.
Inverse property of multiplication.
Answer:
(-3,-4)
Step-by-step explanation:
