Hello!
Remember that the sum of triangle angles are 180 degree.
Based on this we can make a equation for number 1.
(15x+1)+(6x+5)+(4x-1)=180
25x+5=175
25x=175
x=7
For number 2 we can solve the third angle of the two traingles using the method above.
180-80-53=47
180-50-62=68
With the two angle we can solve the third angle of the small triangle which is 180-47-68=75.
See that x and 75 have the same angle because they are all across from two lines so that x=75.
Have a great day!
