Răspuns :
f= nr fetelor
b= nr baietilor
f+b=35
f=75/100 ×b
75/100 ×b+b=35
3/4 ×b+b=35
3b/4 + 4b/4=140/4 |×4
3b+4b=140
7b=140 |:7
b=20
b + f = 35
f = 3b/4
3b/4 + b = 35
3b + 4b = 140
7b = 140
b = 20 baieti
f = 15 fete
f= nr fetelor
b= nr baietilor
f+b=35
f=75/100 ×b
75/100 ×b+b=35
3/4 ×b+b=35
3b/4 + 4b/4=140/4 |×4
3b+4b=140
7b=140 |:7
b=20
b + f = 35
f = 3b/4
3b/4 + b = 35
3b + 4b = 140
7b = 140
b = 20 baieti
f = 15 fete