English is terrible.
1.5 more than last year means you take last year's amount, then add 1.5 times as much.
So if they had 2 coats of arms last year, the math becomes 2 + ( 2 x 1.5 ) = 5 coats of arms.
If they had 3 coats of arms, then it's 3 + ( 3 x 1.5 ) = 7.5 coats of arms.
What you want to...