English test question

Today I had the English Formative Assesments in which the following question was asked from the "unseen" reading passage.

The sentence was-

"The solar-panel presently will set you back about seven times the annual cost of your mains electricity."

Question-Acc to the author, the present cost of establishing rooftop solar-panels is

a) 7 times less that the total electricity bill an avg consumer pays annually.

b)  7 times more that the total electricity bill an avg consumer pays annually.

Option (c) and (d) were completely irrelevant, so I ommited them. I have written option (b) as the answer. Am I right?

[I study in Standard/Class/Form 9]

"kaynight, the master of witty comments." You wanted to hear this, didn't you? Well OK OK  OK don't reply I don't want my post to be plagued by meaningless posts.

I didn't only mean it, I used it! 

Yeah! It means I am correct! 

Another question.

Q)Fill in a suitable preposition-

My uncle suggested that I do a summer job (f)_______ a multinational company.

(f) a}in   b}on  c}for   d}at

I went with d}at. Some of my teachers have been suggesting a}in and some d}at. I surfed the internet and came up with the conclusion that both of them are equally acceptable.

Thanks, kaynight.