I'll try to detail as much as possible the solution to exercise 2. Exercises 4 and 5 and basically identical: you'll have to set up a system translating the sentences to equations, and solve it. Please try to solve exercises 4 and 5 on your own (that's when you really learn!!) by mimicking how I solved exercise 2.
Let's call the three angles
(small, medium and large, respectively). The first sentence translates to

The second sentence translates to

Since we have three unknowns, we need a third equation: this equation is implicit, because we know that the sum of the angles of a triangle is always 180 degrees:

So, we have the following system (rearranged in standard form):

If you subtract the first equation from the third you get

Plug this value for
in the second equation:

Finally, complete to 180 to compute
:

So, the angles are 35, 50 and 95 degrees