\( 2x = 15 - 7 \)
\( 2x = 8 \)
\( x = \frac{8}{2} \)
\( x = 4 \)
\( 3x = 4 + 5 \)
\( 3x = 9 \)
\( x = \frac{9}{3} \)
\( x = 3 \)
\( 7x = 22 \)
\( x = \frac{22}{7} \)
\( 8x - 3x = 13 + 7 \)
\( 5x = 20 \)
\( x = \frac{20}{5} \)
\( x = 4 \)
Ответ: а) 4; б) 3; в) \(\frac{22}{7}\); г) 4.