To increase and amount by 17.5 which single multiplier would you use?

I suppose that the question is 17.5 %.

To increase an amount by a percentage, the multiplier is given by (100 + %)/100

Therefore, to increase an amount by 17.5%,
the single multiplier is given by (100 + 17.5)/100 = 117.5/100 = 1.175

Heptagon is the correct ans