Math
posted by Samantha on .
The sum of 3 numbers is 45. The first number is 4 times the second, while the third is 9 more than the second. Create an equation and solve.

x = 2nd number
4x + x + (x + 9) = 45
6x + 9 = 45
6x = 36
x = 6 
x+y+z=45
x=4y
z=y+9
4y+y+y+9=45
6y=36
y=6
... 
a = first number
b = second number
c = third number
a = 4 b
c = b + 9
a + b + c = 45
4 b + b + b + 9 = 45
6 b + 9 = 45 Subtract 9 to both sides
6 b + 9  9 = 45  9
6 b = 36 Divide both sides by 6
6 b / 6 = 36 / 6
b = 6
a = 4 b
a = 4 * 6 = 24
c = b + 9
c = 6 + 9 = 15
First numer 24 , second number 6 , third number 15
a + b + c = 45
24 + 6 + 15 = 45
45 = 45 
thank you now i understand , i got the answer but i made a mistake on the equation