The answers are..
6. 55
7. 6
8. 39
9. 17
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
Solve;
If each cm = 4 meters, then you multiply.
4*2
= 8
There are 2 cm, each cm = 4 meters, so you multiply to get your answer.
The final height of the door is 8 meters.
The answer would be
1/3 * 9 = 3,
3^3 = 3*3*3, which then we multiply:
3*3=9, 9*3=27.
27 is the answer.
Hope this helps and have a nice day:)
The solution depends on the value of

. To make things simple, assume

. The homogeneous part of the equation is

and has characteristic equation

which admits the characteristic solution

.
For the solution to the nonhomogeneous equation, a reasonable guess for the particular solution might be

. Then

So you have


This means


and so the general solution would be