a, 5 x 4 + 9 x 5 - 5 x 3  - 10

= 5 x ( 4 + 9 - 3) - 10

= 5 x ( 13 - 3) - 10

= 5 x 10 - 10

= 40 

b, 4 x 7 + 4 x 6 - 4 x 3 - 4

= 4 x 7 + 4 x 6 - 4 x 3 - 4 x1

= 4 x ( 7 + 6 - 3 -1)

= 4 x 9

= 36

`5xx4+9xx5-5xx3-10`

`= 5 xx (4+9-3 -10)`

`= 5 xx 0`

`=0`

`-----`

`4 xx7 + 4 xx6 - 4xx3-4`

`=4 xx7 + 4 xx6 - 4xx3-4 xx 1`

`=  4xx (7+6-3-1)`

`= 4 xx 9`

`=36`

5.4 + 9.5 - 5.3 - 10

=5.4 + 9.5 - 5.3 - 5.2

=5.(4 + 9 - 3 - 2 )

=5. 8

= 40

b, 4 . 7 + 4 . 6 - 4 . 3 - 4

=4. ( 7 + 6 - 3 - 1 )

= 4. 9

= 36

a; \(\dfrac{2}{5}\) x \(\dfrac{3}{4}\) + \(\dfrac{6}{15}\) : \(\dfrac{4}{9}\) x 5

  = \(\dfrac{3}{10}\) + \(\dfrac{2}{5}\) x \(\dfrac{9}{4}\) x 5

= \(\dfrac{3}{10}\) + \(\dfrac{9}{10}\) x 5

= \(\dfrac{3}{10}\) + \(\dfrac{45}{10}\)

= \(\dfrac{48}{10}\)

= \(\dfrac{24}{5}\)

b; \(\dfrac{25}{12}\) x \(\dfrac{18}{35}\) x \(\dfrac{63}{24}\)

=   \(\dfrac{15}{14}\) x \(\dfrac{63}{24}\)

= \(\dfrac{45}{16}\) 

c; 4\(\dfrac{1}{2}\) + \(\dfrac{1}{2}\) : 5\(\dfrac{1}{2}\)

= \(\dfrac{9}{2}\) + \(\dfrac{1}{2}\) : \(\dfrac{11}{2}\)

 = \(\dfrac{9}{2}\) + \(\dfrac{1}{11}\)

= \(\dfrac{99}{22}\) + \(\dfrac{2}{22}\)

=  \(\dfrac{101}{22}\)

809703

30

24

45

35

30

24

45

35

6 * 5 = 30

4 * 6 = 24

9 * 5 = 45

7 * 5 = 35

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