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1) 5 + (-4) = 1
2) (-8) + 2 = -6
3) 8 + (-2) = 6
4) 11 + (-3) = 8
5) (-11) + 2 = -9
6) (-7) + 3 = -4
7) (-5) + 5 = 0
8) 11 + (-12) = -1
9) (-18) + 20 = 2
10) (15) + (-12) = 3
11) (-17) + 17 = 0
12) 16 + (-2) = 14
13) (30) + (-14) = 16
14) (-19) + 20 = 1
15) (-18) + 15 = -3
16) (10) + (-6) = 4
17) (-28) + 14 = -14
18) 15 + (-30) = -15
19) (15) + (-4) = 11
20) (-21) + 11 = -10
21) 8 + (-22) = -14
22) (-15) + 4 = -11
23) (-3) + 2 = -1
24) 17 + (-14) = 3
25) 17 + (-14) = 3
a: \(\dfrac{3}{5}-\dfrac{7}{4}=\dfrac{12}{20}-\dfrac{35}{20}=\dfrac{-23}{20}\)
b: \(\dfrac{4}{5}:\dfrac{-8}{15}=\dfrac{-4}{5}\cdot\dfrac{15}{8}=\dfrac{-60}{40}=\dfrac{-3}{2}\)
c: \(=7+\dfrac{5}{9}-2-\dfrac{3}{4}-3-\dfrac{5}{9}=2-\dfrac{3}{4}=\dfrac{5}{4}\)
d: \(=\dfrac{-3}{7}\left(\dfrac{4}{19}+\dfrac{15}{19}\right)+\dfrac{5}{7}=\dfrac{2}{7}\)
1, 3/5 + -4/15 = \(\dfrac{9}{15}\)+ \(\dfrac{-4}{15}\)= \(\dfrac{5}{15}\)= \(\dfrac{1}{3}\)
2, -1/3 + 2/5 + 2/15= \(\dfrac{-5}{15}+\dfrac{6}{15}+\dfrac{2}{15}\)=\(\dfrac{3}{15}=\dfrac{1}{5}\)
3, -3/5 + 7/21 + -4/5 + 7/5= \(\dfrac{1}{3}\)
\(1.\dfrac{3}{5}+\dfrac{-4}{15}=\dfrac{9}{15}+\dfrac{-4}{15}=\dfrac{5}{15}=\dfrac{1}{3}\)
\(2.\dfrac{-1}{3}+\dfrac{2}{5}+\dfrac{2}{15}=\dfrac{-5}{15}+\dfrac{6}{15}+\dfrac{2}{15}=\dfrac{3}{15}=\dfrac{1}{5}\)
\(3.\dfrac{-3}{5}+\dfrac{7}{21}+\dfrac{-4}{5}+\dfrac{7}{5}=\left(\dfrac{-3}{5}+\dfrac{-4}{5}+\dfrac{7}{5}\right)+\dfrac{7}{21}=0+\dfrac{7}{21}=\dfrac{1}{3}\)
\(5:\dfrac{3}{4}-4=5.\dfrac{4}{3}-4=\dfrac{20}{3}-4=\dfrac{80}{12}-\dfrac{48}{12}=\dfrac{8}{3}\)
\(\dfrac{4}{5}:\dfrac{3}{4}=\dfrac{4}{5}.\dfrac{4}{3}=\dfrac{16}{15}\)
\(5:\dfrac{3}{4}-4\dfrac{4}{5}:\dfrac{3}{4}\)
=\(5.\dfrac{4}{3}-4\dfrac{4}{5}.\dfrac{4}{3}\)
=\(\dfrac{4}{3}.\left(5-4\dfrac{4}{5}\right)\)
=\(\dfrac{4}{3}.\left(1-\dfrac{4}{5}\right)\)=\(\dfrac{4}{3}.\dfrac{1}{5}=\dfrac{4}{15}\)