Method of substitution a+3b=5 and 7a-8b=6

Which of the following three dimensional figures has a circle as it’s base

When you dilate a figure with a scale factor of 1/2, what will the dilated figure look like?                                                                                           a: the dilated figure will have side lengths that are half the length of the original side lengths.                                                                          b: the angles in the dilated figure will be half the measure of the original figure.                                                                                c: the dilated figure will have side lengths twice the length of the original.

If u answer this u will get good luck for a year