Question

Determinati a,b,c stiind ca sunt direct proportionale cu 3,11,15 si 3a plus b plus 2c=300

Answer 1

a/3=b/11=c/15      b=11a/3    c=15a/3
3a+b+2c=300
3a+11a/3+2*15a/3=300
9a+11a+30a=900
50a=900
a=18
b=11*18/3=66
c=15*18/3=90

Answer 2

a,b,c dir prop, cu 3,11,15 inseamna ca a/3=b/11=c/15=k asta inseamna ca a=3k b=11k c=15k

3a+b+2c=300
inlocuim
3*3k+11k+2*15k=300
9k+11k+30k=300
50k=300
k=6

a=3*6=18
b=11*6=66
c=15*6=90