Help you answer the questions, sure! Do the problems for you, nope.
in Problem 26 you have 2 small triangles. In the left one you have the angle 36 degrees, which means that the other acute angle is 90-36, or 54 (degrees). You'll need to find the height of the left triangle; finding that height is the same as determining the length of the side adjacent to the 36 degree angle.
Let that height be repr. by h.
Then tan 36 deg = h/21 Use the inverse tangent function to find the value of h.
Look at the triangle on the right. It has a 42 deg angle, and the length of the side next to it is h (which you found above). x is the hypotenuse.
Can you see that x*cos 42 deg = h? Knowing h, can you now find x?
If you have any qu. about this approach, please ask questions.