12+45-23.34:21+234-67:7
= 12+45-782:21+234-\(\frac{67}{7}\)
= 12+45-\(\frac{782}{21}\)+234-\(\frac{67}{7}\)
= \(\frac{415}{21}\)+ \(\frac{1571}{7}\)
= \(\frac{5128}{21}\)
Hk tốt
12 + 45 - 23 x 34 : 21 + 234 - 67 : 7
12 + 45 - \(\frac{782}{21}\)+ 234 - \(\frac{67}{7}\)
= \(\frac{415}{21}\) + 234 - \(\frac{67}{7}\)
= \(\frac{5329}{21}\)- \(\frac{67}{7}\)= \(\frac{5128}{21}\)