This is to help people. in this question The bob (weight) at the end of a pendulum has a mass of 0.3 kilograms. The bob is pulled to position B and allowed to swing. It goes all the way to position C and swings back.

The potential energy of the bob at position B is joules. If the maximum height of the bob is 0.45 meters when it swings back, ___joules of energy was transformed to thermal energy.
Use g = 9.8 m/s2 and PE = m × g × h.

so, if you have the picture on your screen then at the top you will see 0.5 as the height. So, to get the first answer your going to do 0.3(m)x9.8(g)x0.25(h). That will give you the answer. I wont say what it is cause you need to multiply it yourself and see how that works. And for the second part you do the same exact thing except instead of 0.25 its 0.45. I hope this helps you :)