Question

solved question number 7

Answer 1

90,110
because
$90 \times 10\% = 9$
and,
$90 + 9 = 99$
and,
$110 \times 10\% = 11$
so,
$110 - 11 = 99$

Answer 2

cost 1 = 99
$\times \frac{10}{100}$
$99 \times \frac{10}{100}$