Уравнение7х+12=99, 81х-43=200, 15х(25-у)=45

Question

Уравнение
7х+12=99, 81х-43=200, 15х(25-у)=45

Answer 1

1) 7x +12=99
7x=87
x=12.4
2)81x-43=200
81x=243
x=3
3)15x(25-y)=45
375x-15xy=45