Question

determine o valor de x : a) x/5=16/20 b) 9/10=x+10/10

Answer 1

a) x/5 = 16/20
   x = 16/20 . 5
   x = 0,8 . 5
   x = 4
 
b) 9/10= x+10/10
    0,9 = x +1
    x = 1-0,9
    x = 0,1

Espero ter ajudado!

Answer 2

A) $\frac{x}{5} = \frac{16}{20} \\ \frac{4x}{20} = \frac{16}{20} \\ 4x=16 \\ x= \frac{16}{4} \\ x=4$


B) $\frac{9}{10} =x+ \frac{10}{10} \\ \frac{9}{10} = \frac{10x}{10} + \frac{10}{10} \\ 9=10x+10 \\ -10x=10-9 \\ -x=1>>(-1) \\ x=-1$