Question

(50 · 7) + (5 · x) = 510

Answer 1

350 + 5x = 510
5x = 510 - 350
x = 160/5
x = 32

Answer 2

Olá!

$(50 \times 7) + (5 \times x) = 510 \\ 350 + 5x = 510 \\ 5x = 510 - 350 \\ 5x = 160 \\ x = \frac{160}{5} \\ \\ \boxed{x = 32}$

Espero ter ajudado! :)