Question

bài 1 tính

a)1/3   + 1/5  -1/4    =.............................................

                             ..............................................

b)7/8 - (1/4+2/5)=.........................................

                       =..........................................

Answer 1

a: =20/60+12/60-15/60=17/60

b: =7/8-1/4-2/5=5/8-2/5=25/40-16/40=9/40

Answer 2

\(a,\dfrac{1}{3}+\dfrac{1}{5}-\dfrac{1}{4}=\dfrac{20}{60}+\dfrac{12}{60}-\dfrac{15}{60}=\dfrac{17}{60}\\ b,\dfrac{7}{8}-\left(\dfrac{1}{4}+\dfrac{2}{5}\right)=\dfrac{7}{8}-\dfrac{13}{20}=\dfrac{9}{40}\)