Simple Triangle Arithmetic

Geometry Level 2

If a triangle has 3 angles, one of which is x+10, and two of which are of which is x+25, what is the value of x?

50 30 35 40 45

2 solutions

Mahdi Raza
Jun 3, 2020

Sum of angles in any triangle is $180^{\circ}$

$\begin{aligned} \bigg( x+ 10\bigg) + \bigg( x+ 25\bigg) + \bigg( x+ 25\bigg) &= 180 \\ 3x + 60 &= 180 \\ 3x &= 120 \\ x &= \boxed{40} \end{aligned}$

A Former Brilliant Member
Jun 3, 2020

The sum of the angles of a triangle is 180, so the sum x+10+x+25+x+25 must equal 180.

Combining the like terms we get: 3x+60=180

Subtracting 60 from both sides we get: 3x=120

Dividing both sides by 3 we get: x=40

So x=40