Here is the equation with masses:
$"0.9827 g C"_a"H"_b"O"_c + "(1.900 g + 1.070 g - 0.9827 g) O"_2 rarr "1.070 g H"_2"O" + "1.900 g CO"_2$
Use 32.00 g/mol for the molar mass of $"O"_2$
Use 18.03 g/mol for the molar mass of $"H"_2"O"$
Use 44.01 g/mol for the molar mass of $"CO"_2$
We do not know the molar mass of the hydrocarbon so we allow $a, b$, and $c$ to be any positive real number.
$"C"_a"H"_b"O"_c+ ("1.9873 g")/("32.00 g/mol") "O"_2 rarr ("1.070 g")/("18.03 g/mol") "H"_2"O" + ("1.900 g")/("44.01 g/mol") "CO"_2$
Perform the division:
$"C"_a"H"_b"O"_c+ ("0.06210 mol") "O"_2 rarr ("0.05935 mol") "H"_2"O" + ("0.04317 mol") "CO"_2$
Matching coefficients, we get:
$a = 0.04317$
$b = 2 xx 0.05935 = 0.1187$
$c = 0.05935 + 2 xx 0.04317 - 2 xx 0.06210 = 0.02149$
Divide every number by 0.02149:
$a/0.02149 = 2.009$
$b/0.02149 = 5.523$
$c/0.02149 = 1$
Multiply every number by 2:
$2.009 xx 2 = 4.018$
$5.523 xx 2 = 11.05$
$1 xx 2 = 2$
Round off each number to the nearest integer.
$4.018 ≈ color(white)(l)4$
$11.05 ≈ 11$
$color(white)(ll)2color(white)(ml) =color(white)(ll) 2$
The empirical formula is $"C"_4"H"_11"O"_2$.