[tex]27 + 13x = 92 \\ 13x = 92 - 27 \\ 13x = 65 \\ x = 65 \div 13 \\ x = 5[/tex]

[tex](302 - c) \times 3 = 861 \\ 302 - c = 861 \div 3 \\ 302 - c = 287 \\ c = 302 - 287 \\ c = 15[/tex]

[tex]3402 \div (a + 34) = 63 \\ a + 34 = 3402 \div 63 \\ a + 34 = 54 \\ a = 54 - 34 \\ a = 20[/tex]