Respuesta :

4(5-a) - 2.1(6a)= -4.9
20 -4a - 12.6a = -4.9
20 -16.6a = -4.9
subtract 20 to both sides
20 -16.6a -20 = -4.9 -20
-16.6a = -24.9
divide both sides by -16.6
-16.6a/-16.6 = -24.9/-16.6
simplify
a = 1.5