Question

5x+2y=100. lg x - lg y = lg 16-1

Answer 1

lg x - lg y = lg 16 - 1 = lg 16 - lg 10
lg (x/y) = lg (16/10) = lg (8/5)
x/y = 8/5
x = 8y/5
Подставляем в 1 уравнение
5*8y/5 + 2y = 100
8y+2y=10y=100
y=100/10=10
x=8y/5=80/5=16