We will have the following:
First, we remember that suplementary angles add to 180°; knowing this, we can see that the supplementary angle for
We also remember that the sum of internal angles of a triangle also add to 180°, so the following is true:
![m<\text{ACB}+m<\text{CAB}+m<\text{ABC}=180](https://img.qammunity.org/2023/formulas/mathematics/high-school/acapo6gk5vs2o0fflp9sxd7nnvsjyc9db3.png)
So:
![(3x)+(2x+40)+(180-(7x+10))=180\Rightarrow(3x)+(2x+40)+(170-7x)=180](https://img.qammunity.org/2023/formulas/mathematics/high-school/ewshflg57zbshghtu6ym9e7q446pi8mwh7.png)
Now, we solve for x, that is:
![\Rightarrow(3x)+(2x+40)+(170-7x)=180\Rightarrow-2x+210=180](https://img.qammunity.org/2023/formulas/mathematics/high-school/1agn18p08vc9qkngg2aih5tqlk2d9zfbd7.png)
![\Rightarrow-2x=-30\Rightarrow x=15](https://img.qammunity.org/2023/formulas/mathematics/high-school/q2jy7tj44ysz7ang2ffl21gj21frw8sr11.png)
Now, knowing this we will find the measure of angle ABC, that is:
[tex]m<\text{ABC}=170-7x\Rightarrow mSo,
the measure of the angle ABC is 65°.