Question 146667
E = hours of electrician
C = carpenter
P = plumber

21E + 19.5C + 24P = 469.5
P = C + 2
E + P + C = 21.5
Substitute
E + (C+2) + C = 21.5
E + 2C = 19.5
Sub again
21E + 19.5C + 24(C+2) = 469.5
21E + 43.5C = 421.5
42E + 87C = 843
14E + 29C = 281
E = 19.5 - 2C
Sub again for E
14(19.5 - 2C) + 29C = 281
273 - 28C + 29C = 281
C = 8
P = 10
E = 3.5
Check - 8*$19.50 + 10*$24 + 3.5*$21 = $469.50