Respuesta:
a) x = 13
b) x = 25
c) y = 15.66
d) c= -9
Explicación paso a paso:
a) x+ 5 = 3x - 21
x - 3x = - 21 - 5
-2x = - 26
2x = 26
x = 26/2
x= 13
b) 2x - 45 = x -20
2x - x = -20 + 45
x = 25
c) 3y + 9 = 56
3y = 56 - 9
3y = 47
y = 47/3
y = 15.66
d) 5c - 45 = 6c - 36
5c - 6c = -36 + 45
- c = 9
c = - 9