The sum of the measures of the angles of a triangle is 180. The sum of the measures of the second and third angles is nine times the measure of the first angle. The third angle is 20 more than the second. Let x, y, and z represent the measures of
the first, second, and third angles, respectively. Find the measures of the three angles,
balor

Divide the measure of all 3 angles into 10 parts...1 part is the measure of angle x, and the other angles add up to the other 9 parts. 180/10=18...so x = 18.
So angle y and z together add up to the other 162 degrees.
Divide 162 in half to find the “middle”...162/2=81.
Since we were told that the difference between y and z is 20...y would be 10 less than that middle number, and z would be 10 more than it...so y=71, and z=91.
The answers are...
X=18, Y =71, Z=91

J= r + 9 because since jessica rode 9 more miles than roger, you add 9 miles to rogers mileage.