According to boyle's law

(P + ΔP) (V - ΔV) = PV

(P + ΔP) (V - 0.1 V) = PV

PV + VΔP - 0.1 PV - 0.1 VΔP = PV

0.9 V ΔP = 0.1 PV

\(\frac{ΔP}{P}\) = \(\frac{1}{9}\)

Percentage increase = \(\frac{ΔP}{P}\) x 100 = \(\frac{100}{9}\) = 11.1

Percentage increase = 11.1 %