Question

Efetue:
A) 7/9 × 21/5=
B) 21/10 ÷ 7/5=
C) 5/6 - 1/4=
Me ajudem por favor é para entregar daqui a pouco!!!

Answer 1

A)

$\frac{7}{9} \times \frac{21}{5}$

$= \frac{147}{45}$

$= \frac{49}{15}$

_____

B)

$\frac{21}{10} \div \frac{7}{5}$

$= \frac{21}{10} \times \frac{5}{7}$

$= \frac{3}{2}$

_____

C)

$\frac{5}{6} - \frac{1}{4}$

$= \frac{10}{12} - \frac{3}{12}$

$= \frac{7}{12}$

_____

Espero ter ajudado

Answer 2

$\Large\boxed{\begin{array}{l}\sf A)~\dfrac{7}{\diagup\!\!\!9_3}\times\dfrac{\diagdown\!\!\!\!\!\!21^7}{5}=\dfrac{49}{15}\\\sf B)~\dfrac{21}{10}\div\dfrac{7}{5}=\dfrac{\diagdown\!\!\!\!\!\!21^3}{\diagdown\!\!\!\!\!\!10_2}\times\dfrac{\diagdown\!\!\!\!5^1}{\diagdown\!\!\!\!7_1}=\dfrac{3}{2}\end{array}}$

$\Large\boxed{\begin{array}{l}\sf C)\dfrac{5}{6}-\dfrac{1}{4}\\\\\begin{array}{c|c}\rm6,4&\rm2\\\rm3,2&\rm2\\\rm3,1&\rm3\\\rm1,1\end{array}\\\sf m\cdot m\cdot c(6,4)=2\times2\times3=12\\\sf\dfrac{5}{6}-\dfrac{1}{4}=\dfrac{10-3}{12}=\dfrac{7}{12}\end{array}}$