Răspuns :
a+b+c=987
a=30+b=30+1p
c=15+a=15+30+b=45+b=45+1p
b=1p
30+1p+1p+45+p=987
75+3p=987
3p=912
p=304
b=304
a=334
c=349
3copii=987lei
P=30 mai mult decat D
T=15 mai mult decat P
P=primul
D=al doilea
T=al treilea
P+D+T=987
30+D+D+15+P=987
30+2D+15+30+D=987
75+3D=987
3D=987-75
3D=912
D=912:3D=304
D=304lei
P=30+304=334lei
T=15+334=349lei
Verificare:
P+D+T=987 lei
334+304+349=987lei
638+349=987lei