Question

The measures of the three angles of a triangle are given as 18x - 7, 12x + 9, and 4x. What is the measure of the largest angle? Round your answer to the nearest tenth.

Answer 1

Givens
All triangles have 180 degrees
A = 18x - 7
B = 12x + 9
C = 4x
Total 180 degrees.

Equation and Solve
Collect like terms on the left
18x - 7 + 12x + 9 + 4x = 180
18x + 12x +9 - 7 = 180
30x + 2 = 180 Subtact 2
30x = 178 Divide by 30
x = 178 / 30
x = 5.9333333 I

The largest angle is 
5.9333333 * 18 - 7 = 99.8

Answer
Largest Angle = 99.8 <<<< answer

Further Comment
This angle is an obtuse angle. There cannot be a larger one in the same triangle.