Can someone please help me with this and tell me how to work it out

How much orange juice do you need to make 2 servings of lemony orange slush?

John used linear combination to solve the system of equations shown. he did so by multiplying the first equation by -3 and the second equation by another number to eliminate the x-terms. what number did jonas multiply the second equation by? 4x-6y=23x+5y=11

How long must $542 be invested at a rate of 7% to earn $303.52 in interest? in a easier way