In Andrew's number, the value represented by the digit 5 is 10 times the value represented by the digit 5 in 2,356. Which number did Andrew write?

I’m really confused and need your assist me with this question i’ve never been taught

Which expression gives the exact value of x?

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