but to solve for y you should use the first equation that is use the coefficient of x in the first equation to multiply all the terms in the second equation.
And use the coeffient of x in the second equation to multiply the the terms in the first equation.
It would have been better if the equation was shown for better explanation.
650 kgs is equal to 1,433 lbs. I believe the mistake would be that they forgot to add a period in between 65 and the 0, because 65.0 kgs is equal to 143.3 lbs.