Question

Daca a+b=20 si b+c=30, calculati 3.a +7.b+4.c Factor comun

Answer 1

3a+7b+4c=

3a+3b+4b+4c=

3(a+b)+4(b+c)=

3x20+4x30=

60+120=

180

Answer 2

3.a+7.b+4.c=3.a+3.b+4.b+4.c

a+b=20 => 3.a+3.b=60

b+c=30 => 4.b+4.c=120

=>3.a+3.b+4.b+4.c=120+60=180