b) 720 : ( a × 3 + a × 5) = 2 × 3
Giải thích
b) 720 : ( a × 3 + a × 5) = 2 × 3
720 : a x ( 3 + 5 ) = 6
720 : a x 8 = 6
a x 8 = 720 : 6
a x 8 = 120
a = 120 : 8
a = 15
b) 720 : ( a × 3 + a × 5) = 2 × 3
720 : a x ( 3 + 5 ) = 6
720 : a x 8 = 6
a x 8 = 720 : 6
a x 8 = 120
a = 120 : 8
a = 15