Answer:
x=25
Step-by-step explanation:
x+y=100 (y being number of 8¢ stamps)
12x+ 8y = 900
-----------------------------------
y = 100-x
12x + 8y = 900
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12x + 8(100-x) = 900
12x + 800 - 8x = 900
12x - 8x = 900 - 800
4x = 100
x=25
Answer:
an = -2 -3(n-1)
Step-by-step explanation:
an = a1+(n-1) d
a1 =-2
d = -5--2
d = -5+2
d=-3
we are decreasing by 3 each time
an = -2 + (n-1) * -3
an = -2 -3(n-1)
Answer: 
Step-by-step explanation:
The sum of 10 consecutive integersstarting with 11
= 11 + 12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20 = 155
Lets try 29:
29 + 30 + 31 + 32 + 33 = 155
Therefore our answer is:

Hi it is 7n I hope I was right
Answer:
option c
Step-by-step explanation:
<em>Step 1: Multiply each number in matrix A by -4</em>
( -4x-4 -4x-4 1x-4 )
( 1x-4 4x-4 7x-4)
( 2x-4 3x-4 3x-4)
( 16 16 -4 )
( -4 -16 -28)
( -8 -12 -12)
<em>Step 2: Multiply each number in matrix B by 8</em>
( 2x8 9x8 -9x8 )
( 8x8 8x8 -2x8 )
( 4x8 10x8 1x8 )
( 16 72 -72 )
( 64 64 -16 )
(32 80 8 )
<em>Step 3: Form the matrix of -4A + 8B by adding the correspondent numbers in the matrix.</em>
( 16+16 16+72 -4-72 )
( -4+64 -16+64 -28-16 )
( -8+32 -12+80 -12+8)
( 32 88 -76 )
( 60 48 -44)
( 24 68 -4 )
Therefore option c is correct.
!!