1. x = 12·15 / 10 =180 /10 =18
2. 213 :71 =3 natural A
3. x = 5y /7 ( 5y/7 + y ) :y = 12 y /7 :y = 12 /7 F
4. 15%· 40 = 15· 40 /100 =600/100 = 6
40 +6 =46 F
5.125%·32 = 125 ·32 /100 = 4000/100=40
6. 9x + 9= 36 ; 9x = 36 - 9 ; 9x = 27 ; x=3
7. x= 21·5 /7 = 15 ; y =10 ·7 /5 =14 x+y=15+14=29