a, 42,6 x 24 + 24 x 57,4
= 24 x ( 42,6 + 57,4 )
= 24 x 100
= 2400
b, 1$\dfrac{1}{2}$ - ( 0,5 - $\dfrac{1}{3}$ ) x $\dfrac{3}{5}$
= $\dfrac{3}{2}$ - ( $\dfrac{1}{2}$ - $\dfrac{1}{3}$ ) x $\dfrac{3}{5}$
= $\dfrac{3}{2}$ - $\dfrac{5}{6}$ x $\dfrac{3}{5}$
= $\dfrac{3}{2}$ - $\dfrac{1}{2}$
= $\dfrac{2}{2}$
= 1
$\text{~ Học tốt}$
