$\text{a) 135 + 65 × 15 - 9898 ÷ 98.}$
$\text{= 135 + 975 - 101.}$
$\text{= 1110 - 101.}$
$\text{= 1009.}$
$\text{b) 19,35 × 99 + 19,35.}$
$\text{= 19,35 × 99 + 19,35 × 1.}$
$\text{= 19,35 × (99 + 1).}$
$\text{= 19,35 × 100.}$
$\text{= 1935.}$
$\text{c) 215 × 15 + 31 × 45 - 6363 ÷ 63.}$
$\text{= 215 × 15 + 31 × 3 × 15 - 6363 ÷ 63.}$
$\text{= 215 × 15 + 93 × 15 - 6363 ÷ 63.}$
$\text{= (215 + 93) × 15 - 6363 ÷ 63.}$
$\text{= 308 × 15 - 6363 ÷ 63.}$
$\text{= 4620 - 101.}$
$\text{= 4319.}$
$\text{Cho anh xin câu trả lời hay nhất, 5 sao và cảm ơn}$