His mistake was in multiplying the 3 with the 12. He should have divided it from the 12 because that would have gotten rid of the 3 with the variable. It would also lead to the correct answer, which is b=4
X+y=155. Y= -x+155
1.50x +4(-x+155)= 520
1.50x-4x+620=520
-2.5x =-100
X= 40. Y=110
Just subtract the number infront of missing number to the opposing number
Let h = the number of horses in the field
Let c = number of cows in the field
There are 2 more horses than cows in the field. Therefore
h = c + 2
or
c = h - 2 (1)
There are 15 animals in the field. Therefore
h + c = 15 (2)
Substitute (1) into (2).
h + (h - 2) = 15
2h - 2 = 15
Answer:
The correct equation is
2h - 2 = 15
