How do you solve this? if you can answer on paper

∠?=40°

Step-by-step explanation:

Remember that in a line AND a triangle there are 180 degrees.

You correctly found the third angle in the left triangle to be 69°, Now plug it into the equation for a line, including 71°:

69°+71°+x=180°

1) Combine the degrees:

140°+x=180°

2) Subtract 140° from both sides:

x=40°

We have now found the bottom left angle for the triangle on the right to be 40°

To find the angle labeled "?" You must plug in all of the known angles of the triangle to be equal to 180°:

40°+100°+x=180°

1) Combine the degrees:

140°+x=180°

2) Subtract 140 from both sides:

∠?=40°

-2 is the right