Tính thuận tiện a)15,27-4,18-2,09 b)45,28+52,17-15,28-12,17 c)54,27+16,9-2,27 d)7/15+7/4+8/15+5/4

a, 15,27 – 4,18 – 2,09 

= ( 15,27 – 4,18 ) – 2,09

= 11,09 – 2,09

= 9

b, 45,28 + 52,17 – 15,28 – 12,17

= ( 45,28 – 15,28 ) + ( 52,17 – 12,17 )

= 30 + 30 

= 60

c, 54,27 + 16,9 – 2,27

= ( 54,27 – 2,27 ) + 16,9

= 52 + 16,9

= 68,9

d, $\frac{7}{15}$  + $\frac{7}{4}$  + $\frac{8}{15}$ + $\frac{5}{4}$ 

= ( $\frac{7}{15}$ + $\frac{8}{15}$ ) + ( $\frac{7}{4}$ + $\frac{5}{4}$ )

= 1 + 3

= 4