\(a,\dfrac{2}{5}+\dfrac{3}{4}:2=\dfrac{2}{5}+\dfrac{3}{8}=\dfrac{16}{40}+\dfrac{15}{40}=\dfrac{31}{40}\)
\(b,\dfrac{1}{2}\times\left(\dfrac{5}{2}-\dfrac{3}{5}\right)=\dfrac{1}{2}\times\dfrac{19}{10}=\dfrac{19}{20}\)
a: =2/5+3/8=16/40+15/40=31/40
b: =1/2x(25/10-6/10)
=1/2x19/10=19/20
a) 2/5+ 3/4 : 2
= 2/5 + 3/8
= 16/40 + 15/40
= 31/40
b) 1/2 x ( 5/2- 3/5)
= 1/2 x ( 25/10 - 6/10)
= 1/2 x 19/10
= 19/20