1) 2(4a+9)=3(5b+6)
8a+18=15b+18
8a=15b
a/b=15/8
2) x/y=5/3 inseamna ca x=2k si y=3k si inlocuiesc in x-y=10 5k-3k=10
2k=10 deci k=2
x=5k=5×5=25 y=3k=3×5=15
b) x/y=3/5 si 3x-y=12
x=3k si y=5k si inlocuim 3*3k-5k=12⇒9k-5k=12
4k=12⇒k=3,,,,, deci x=3*3=9 si y=5*3=15
