Let
x-------> the cost of the burger
y-------> the cost of the <span>sandwiches
we know that
3x+2y=27-----> equation 1
2x+y=27-11-----> 2x+y=16-----> multiply by -2-----> -4x-2y=-32--> equation 2
adds equation 1 and equation 2
</span> 3x+2y=27
-4x-2y=-32
<span>----------------
-x=27-32-----> x=5
3*5+2y=27----> 2y=27-15-----> y=6
therefore
the answer is the option
</span><span>3) The student's conclusion is correct because the solution to the system of equations 3x + 2y = 27 and 2x + y = 16 is (5, 6).</span>
n(A-B) denotes elements which are in A but not in B
n(Au B) denotes elements in A and B
n(AnB) denotes elements that are common in A and B
Now I will add one more set
n(B-A) which denotes elements in B but not in A
So, n(AuB) = n(A-B) + n( B-A) +n(AnB)
70 = 18 +n(B-A) + 25
70 = 43 + n(B-A)
n(B-A) = 70-43
n(B-A) = 27
So, n(B) = n( B-A) + n( AnB)
= 27+25
= 52
If you would like to solve the system of equations 5x + 4y = 12 and 3x - 3y = 18 using elimination, you can do this using the following steps:
<span>5x + 4y = 12 /*3
3x - 3y = 18 /*4
_____________
15x + 12y = 36
12x - 12y = 72
_____________
15x + 12y + 12x - 12y = 36 + 72
15x + 12x = 36 + 72
27x = 108
x = 108/27
x = 4
</span><span>3x - 3y = 18
</span>3 * 4 - 3y = 18
12 - 3y = 18
12 - 18 = 3y
3y = -6
y = -6/3
y = -2
(x, y) = (4, -2)
The correct result would be: x = 4 and y = -2.
Answer: 30 - 5 = 25 (the difference between the two is 5)