Question

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Answer 1

you should have 2x = 10 and NOT x = 10

Answer 2

you forgot to add the x terms x+x = 2x

Answer 3

it's always good to determine y though without looking at the multiple choice answers

Answer 4

you have 3 equations, 2 variables?

Answer 5

what are the equations again?

Answer 6

do you know how to write the left side as a matrix?

Answer 7

you just write the numbers in a matrix like this