Respuesta :

4m-21=3(5m-1)
4m-21=15m-3
-21+3=15m-4m
-18=11m
m= - 18/11
 
check
4*(-18/11)-21=3(5*(-18/11)-1)
-72/11-(21*11)/11=3(-90/11-11/11)
-72/11-231/11=3*(-101/11)
-303/11≡ -303/11 true,

so
m= - 18/11 is a solution