Answer:
-10 is not a solution to the equation
Step-by-step explanation:
I don't really have an explanation
Answer:

Step-by-step explanation:
we have:

we also have:

from (1)(2) => proven
Answer:
15 boys and 25 girls
Step-by-step explanation:
The sum of boys (b) and girls (g) is given as 40:
g + b = 40
The number of girls is 2 times the number of boys minus 5:
2b - 5 = g
First formula can be rewritten as g = 40 - b
Then you can substitute this for g in the second, and you get:
2b-5 = 40-b
Which simplifies to:
2b + b = 40 + 5
3b = 45
b = 15
g = 40-15 = 25
15 boys, 25 girls.
Answer:
The last one is correct.
Step by step:
Each income has ONLY one outcome.