The answer is yes most shapes do have line of symmetry for such task. The ones that don't would be irregular shapes or small changes to its handle on more obscure symmetrical shapes, ie) they do not fit in itself due to a handle being rotated before hand, so things that appear to be symmetrical can have a symmetrical line even if they do not fit in their selves at say anything under 360 rotation.
The answer is 24. To get from one term to the next, you have to find the difference. To get from 52 to 45, you minus 7. It is the same with the other terms. So 31 - 7 = 24
