Answer:
y=
1
2
x;−3y=4+
1
2
x
Rewrite equations:
y=
1
2
x;−3y=
1
2
x+4
Step: Solvey=
1
2
xfor y:
y=
1
2
x
Step: Substitute
1
2
xforyin−3y=
1
2
x+4:
−3y=
1
2
x+4
−3
1
2
x=
1
2
x+4
−3
2
x=
1
2
x+4(Simplify both sides of the equation)
−3
2
x+
−1
2
x=
1
2
x+4+
−1
2
x(Add (-1)/2x to both sides)
−2x=4
−2x
−2
=
4
−2
(Divide both sides by -2)
x=−2
Step: Substitute−2forxiny=
1
2
x:
y=
1
2
x
y=
1
2
(−2)
y=−1(Simplify both sides of the equation)
Answer:
x=−2 and y=−1
Step-by-step explanation:
Sorry if it is too confusing
Let's say a = number of ordered soups, b = number of ordered sandwiches.
Then 4.5a + 7.75b = 113.50, and a and b are integers between 0 and 18 inclusive.
How do we tackle this? If all ordered soup, the cost would be $81, so we'll have at least 4 sandwiches. If all ordered sandwich, the cost would be $139.5, so at most 15 sandwiches were ordered. You also know an even number of sandwiches was ordered, to let the price end at 50 cent.
If you brute-force from 4,6,8,10,12 to 14 sandwiches, you find the answer at 10 sandwiches and 8 soups.
10*7.75 + 8*4.50 = 113.50
8x - 3/x
x = 1/2
(8 • 1/2) - 3/0.5
4 - 1.5
2.5
