Answer:
x = 12
Step-by-step explanation:
Total sum of the three angles in any triangles is 180.
In this question, we already know the angles.
So, we will have this equation.
(8x-1) + (3x+9) + (3x+4) = 180
Remove the parentheses.
8x-1 + 3x+9+ 3x+4= 180
Collect like terms and calculate the sum or difference. (I have written terms in bold letters and underlined the numbers.)
14x + 12 = 180
Now, move the constant to the right-hand side and change its sign.
14x = 180 - 12
14x = 168
We want "x", not "14x". So, divide both sides of the equation by 14.
x = 12
I hope it helps.
