Question

7у-у+15у=420


Помогите срочно

Answer 1

21у=420
у=420/21
у=20

Ответ: 20.

Answer 2

$7y - y + 15y = 420 \\ 6y + 15y = 420 \\ 21y = 420 \\ y = 420 \div 21 \\ y = 20$