Question

daca a+b=20 si b+c=23 . Calculeaza 3a+7b+4c

Answer 1

a+b=20

3a+3b=20*3=60

b+c=23

4b+4c=4*23=92

3a+3b+4b+4c=3a+7b+4c=60+92=152

Answer 2

a+b=20=>a=20-b
b+c=23=>b=23-c sau c=23-b
3(20-b)+7(23-c)+4(23-b)
60-3b+161-7c+92-4b=-9-7b-7c=9-7b-7(23-b)=9-7b-161+7b=-152