Well for the first one, that is presumably a straight line and straight lines all have 180 degrees. So you add 61 and 23 to get 84 and subtract that from 180. You then get 96 degree.
For the second one corresponding angles on a transversal are congruent so x+95=4x-10 and then you solve the equation.;
For the third one you need to make the change from 9 to 12 be the same as the change from 3 to t. 9 to 12 is 4/3 so 3 times 4/3 is 4. t=4