An obtuse triangle has one obtuse angle, or an angle that measures more than 90° but less than 180°. Options 1 and 2 are not correct, because these are acute angles.
So, one of the angles must be 40°, and the other may be 100° or 120°.
The measures of the angles in a triangle add up to 180°.

The other two angles are 40° and 100°.
2x² = 7x + 6
Subtract both terms so that we can get 0 on one side.
2x² - 7x - 6 = 0
Find what factors of - 12 (2 * - 6) add up to be - 7. It's - 4 and - 3.
2x² - 4x - 3x - 6 = 0
2x(x - 2) - 3(x - 2) = 0
(x - 2)(2x - 3) = 0
Now set each equal to 0.
x - 2 = 0
x = 2
2x - 3 = 0
2x = 3
x = 3/2
x = 3/2, 2