Question

Реши уравнения 
(80-x)*5+20=370.     (640:y)*9-27=45

Answer 1

(80-x)*5+20=370.  

(80-х)*5=370-20
(80-х)*5=350
80-х=350:5
80-х=70
х=80-70
х=10

(640:y)*9-27=45
(640:y)*9=45+27
(640:y)*9=72
640:y=72:9
640:у=8
у=640:8
у=80