Two angles are called supplementary when their measures add up to 180 degrees.
If angles A and B are supplementary, it means that:

If the measure of angle A is 60 degrees larger than twice the of the supplemental angle B, it can be had that:

Substitute the equation for A into the first equation:

Solving for B:

The measure of angle A can be gotten by substituting the value of B into the equation for A:

The measure of A is 140°.