SOLUTION: The measure of the first angle of a triangle is four times as large as the measure of the second angle. The thrid angle measures 15 less than twice the first angle. Find teh measur

Algebra ->  Angles -> SOLUTION: The measure of the first angle of a triangle is four times as large as the measure of the second angle. The thrid angle measures 15 less than twice the first angle. Find teh measur      Log On


   

Question 714752: The measure of the first angle of a triangle is four times as large as the measure of the second angle. The thrid angle measures 15 less than twice the first angle. Find teh measures of the angle. I start out like this
Angle 1=a
Angle 2=b
Angle 3=c
a=4b
c=2a-15
Equation: 4b+b+2a-15=180.
Because there are two variables on this question im a little confused on how to make this work.
Answer by aliafzal14(13) About Me  (Show Source):
You can put this solution on YOUR website!
as a=4b so b=a/4
so,
4•a/4+a/4+2a-15=180
4•a/4+a/4+2a-15-180=0
5•a/4+2a-195=0
(5a)/4+(2a-195)=0
((5a)+4(2a-195))/4=0
Now we remove the brackets.
(5a+8a-780)4=0

Arrange the terms.
(13a-780)4=0
Let common 13 from the value
(13(a-60))/4=0
(13/4)*(a-60)=0
a-60=0
Let's move the constants to the right-hand side of the equality with the reverse sign.
a=60
The final answer is: a=60

the first angle is =a =60
the second angle is =b =a/4=15
the third angle is = c = 2a -15 = 2(60) -15=120 -15=105