78 + 12 - 40 =

(a)  

$$80\ \ ·\ \ 70\ =$$  

(a)  

$$4\ 500\ -\ 2\ 800\ =$$  

(a)  

$$200\ \ ·\ \ 8\ =$$  

(a)  

1 600 : 40 =

(a)  

$$2,8\ +\ 3,3\ =$$  

(a)  

$$8\ -\ 2,2\ =$$  

(a)  

$$2,4\ \ ·\ \ 3\ =$$  

(a)  

$$2,4\ \ :\ \ 0,3\ =$$  

(a)  

$$50\ \ :\ \ \left(25-15\right)=$$  

(a)  

$$5,6\ +\ 7,4\ =$$  

(a)  

$$20\ -\ 7,7\ =$$  

(a)  

$$0,9\ \ ·\ \ 8=$$  

(a)  

$$450\ :\ 90\ =$$  

(a)  

$$16\ +\ 20\ :\ 4\ =$$  

(a)