Răspuns :
a + b + c = 45
a = 3/5 x b
c = 7/3 x a
c = 7/3 x 3/5 x b
c = 7b/5
3b/5 + b + 7b/5 = 45
3b+5b+7b= 225
15b = 225
b= 225 : 15
b= 15
c= 7 x15/5
c= 21
a= 3x 15/5
a= 9
a = 3/5 x b
c = 7/3 x a
c = 7/3 x 3/5 x b
c = 7b/5
3b/5 + b + 7b/5 = 45
3b+5b+7b= 225
15b = 225
b= 225 : 15
b= 15
c= 7 x15/5
c= 21
a= 3x 15/5
a= 9
a+b+c=45
a=3/5 x b
c=7/3 x a prin inlocuire c=7/3 x 3/5 x b=21/15 x b
a+b+c=45
3/5 x b + b + 21/15 x b = 45
cmmmc=15
3x3xb + 15xb +21xb= 45 x 15
9xb + 15xb + 21xb=675
45xb=675
b=15 a=3/5xb=3/5 x 15 a=9
c=21/15xb=21/15 x 15 c=21
a=3/5 x b
c=7/3 x a prin inlocuire c=7/3 x 3/5 x b=21/15 x b
a+b+c=45
3/5 x b + b + 21/15 x b = 45
cmmmc=15
3x3xb + 15xb +21xb= 45 x 15
9xb + 15xb + 21xb=675
45xb=675
b=15 a=3/5xb=3/5 x 15 a=9
c=21/15xb=21/15 x 15 c=21