Giải thích các bước giải:
B1)
a)`-1/8``+``-5/3`
`=``-3/24``+``-40/24`
`=``-43/24`
b)`-6/35``×``-49/54`
`=``7/45`
c)`-4/5``:``-3/4`
`=``-4/5``×``4/-3`
`=``3/5`
d)`31/17``+``-5/13``+``-8/13``-``14/17`
`=``(`31/17``-``14/17`)`+`(`-5/13``+``-8/13`)
`=``1``+``(-1)`
`=``0`
B2)
a)`4/5``.``x``=``4/7`
⇒`x``=`4/7``÷`4/5`
⇒`x``=``16/35`
b)`3/``4÷``x``=``1/2`
⇒`x``=``3/4``÷``1/2`
⇒`x``=``3/2`