\( 67 + x = 2400 : 8 \)
\( 67 + x = 300 \)
\( x = 300 - 67 \)
\( x = 233 \)
\( y - 143 = 18 \cdot 3 \)
\( y - 143 = 54 \)
\( y = 54 + 143 \)
\( y = 197 \)
\( c \cdot 19 = 2000 - 100 \)
\( c \cdot 19 = 1900 \)
\( c = 1900 : 19 \)
\( c = 100 \)
Ответ: x = 233, y = 197, c = 100.