4) a=w21/8×2/9+3/8
a=42/72+3/8
a=42/72+27/72
a=69/72
Inversul este 72/69
5) (7,6÷4+5,3) la puterea 2÷0,18=(1,9+5,3) la puterea 2÷0,18=7,2 la puterea 2÷0,18=51,84÷0,18=5184÷18=288
6) [(15/4-9/10)×5/19-2] la puterea 2=[(150/40-36-40)×4/19-2] la puterea 2=(114/40×4/19-2) la puterea 2=(456/760-2) La puterea 2=(456/760-1520/760) la puterea 2=-1064/760
