X − 4y = 7
5x + 9y = 6
5x − 20y = 35 //1st * 5
5x + 9y = 6
5x +9y - 5x + 20y = 6 - 35 //2nd - 1st
5x + 9y = 6
29y=-29
5x=6-9y
y=-1 //1st : 29
5x=6-9*(-1)
y=-1
x=15:5 //2nd : 5
y=-1
x=3
check:
for x=3 and y=-1 there is:
x − 4y = 7 is 3 − 4*(-1) = 7 is 7=7 ok
5x + 9y = 6 is 15-9=6 is 6=6 ok
answer: (3;-1) represents the solution.
Answer: 121
Step-by-step explanation:
The total of 2 buckets of popcorn and 3 boxes of candy would be $23.25
To answer this question you need to form a set of simultaneous equations and solve them. We can do this by saying that a bucket of popcorn = P, and a box of candy = C. Then we can say:
4P + 6C = 46.50
P + C = 9.75
There are then two possible ways to solve; you can either say that C = 9.75 - P using the second equation and then substitute it into the first, or you can multiply the second equation by either 4 or 6 to cancel out P or C.
I’m going to multiply the second equation by 4:
4P + 4C = 39
Now we can subtract this for, the first equation:
4P + 6C = 46.50
4P + 4C = 39
2C = 7.50
C = 3.75
Now we can substitute this value of C into one of the equations to find P:
P + C = 9.75
P + 3.75 = 9.75
P = 6
And now to answer the question, you just multiply P by 2 and C by 3 and add them together, which gives you $23.25
I hope this helps! Let me know if you have any questions :)
