Question

Решить систему удобным способом
4x-7y=30
4x-5y=90

Answer 1

1) 12x - 7y = 24x - 5y = 612x - 15y = 18 8y = -16y=-24x+10=64x=-4x=-1 2) 4x - 7y = 30    4x - 5y = 90-2y= -60y=304x - 150=904x=240x=60

Answer 2

4x-7y=30
4x-5y=90
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  -2y=-60
    y=-60:(-2)
    y=30
4x-7y=30
4x-7*30=-30
4x-210=-30
4x=-30+210
4x=180
x=180:4
x=45
(45;30)