All you need to do is convert all equations into standard form by using the distributive property on each equation.
The triangle to solve for has a leg or 12 feet, hypotenuse of 20 feet, so solve for Pythagoras

for a

a = 16 feet
Answer:
d. about 50 times larger
Step-by-step explanation:
The given expressions for magnitude (M) can be solved for the intensity (I). Then the ratio of intensities is ...

The larger earthquake had about 50 times the intensity of the smaller one.
Do the indicated mult. first:
7v - 2v + 16 = 5v + 20
5v + = 5v +20. This is never true. NO solution.
6(x-17) it is disturbing 6
it is 6x-102 or 6x-6.17
so the answer is C