I need help with both please, both answers

X+y=-4 x-y=2 use elimination with adding and subtraction

Examine this system of equations. what integer should the second equation be multiplied by so that when the two equations are added together, the x term is eliminated? 3/4x+1/7y=6 1/8x-3/5y=16

Acontainer holds 0.7 liters of oil and vinegar. 3/4 of the mixture is vinegar. how many liters of oil are in the container? express your answer as both a fraction and a decimal.