tính rồi rút gọn a) (2/5) + (3/6) ; b) (21/30) - (9/30) ; c) (5/8)*(4/7)
Giải thích
a) 25+36=1230+1530=2730=910
b) 2130-930=1230=25
c) 58×47=2056=514
d) 79÷116=79×611=4299=1433
a) 25+36=1230+1530=2730=910
b) 2130-930=1230=25
c) 58×47=2056=514
d) 79÷116=79×611=4299=1433