the answer is 21 it really not it just I have to do this for this app that won't give me these for answers

Actually Welcome to the Concept of the Similarities.
Since here, first figure is a Triangle, hence similarity of a triangle is given by ratio of it sides and make them equate,
hence for,
1.) 16/12 = x/9 ===> 4/3 = x/9 ===> x = 9*4/3 ==> x = 36/3
hence the value of x is 12 , ===> x = 12 .
2.) here,in the case of a Reactangle the relation is such that, length = 2* breadth,
hence we apply the relation,
x = 2*4.5 ===> x = 9 units.
Yes it is because 1/4 + 1/4 =2/4 and 2/4 equals 1/2
Answer:
For this scenario, I used the elimination method. Organize the equations, so it's easier to subtract from each other. My x-variable will represent the number of hot dogs and my y-variable will represent the number of sodas.
3x+2y=213
x + y =87
We need to make sure one of the monomials are alike in each equation, so we can eliminate a variable. Distribute 3 to each number/variable in the second equation.
3x+2y=213
3(x+y=87) --> 3x+3y=261
Now we can eliminate x.
3x+2y=213
- 3x+3y=261
----------------------
-y=-48
Divide -1 to both sides to get y=48. So, you sold 48 cans of soda. Now, we can find the number of hot dogs by substituting 48 into the second equation to get x+48=87. Subtract 48 to both sides to result with x=39. So, you sold 39 hot dogs.