teht. 1,2,3,4,5,6,7

1.
a. $4-15=-11$

b. $-2\cdot\left(-1\right)=-2$

c. $4-10\cdot2\ =\ 4-5\ =\ -1$

d.

$8+2\cdot3-7\ =\ 8+6-7=7$

2.
a. $\frac{43+6}{7\cdot7}=\frac{49}{49}=0$

b.

$\frac{2}{3}+\frac{4}{5}=^{\text{5)}}\frac{10}{15}+^{\text{3)}}\frac{12}{15}$
$=\frac{22}{15}$

c.

$\frac{3}{2}\cdot\frac{4}{5}=\frac{12}{10}$

d.

$\frac{2}{5}:\frac{3}{5}=\frac{2}{5}\cdot\frac{5}{3}=\frac{2}{3}$

3.

a. $0{,}24$ $0{,}06$ $1{,}37$

b.

$\frac{17}{100}$ $\frac{75}{100}$ $\frac{56}{100}$

c,

$90\%$ $60\%$ $150\%$

4,
A, 2
B, 4
C, 3
D, 5
E, 1

5,