Resposta :
[tex]\boxed{\begin{array}{l}\sf7-x=\dfrac{1}{49}\\\sf343-49x=1\\\sf 49x=343-1\\\sf 49x=342\\\sf x=\dfrac{342}{49}\end{array}}\blue{\checkmark} [/tex]
[tex]\boxed{\begin{array}{l}\sf7-x=\dfrac{1}{49}\\\sf343-49x=1\\\sf 49x=343-1\\\sf 49x=342\\\sf x=\dfrac{342}{49}\end{array}}\blue{\checkmark} [/tex]