Evaluate the expression when y= 7 and x = 9.
x + 4y

  [1]    9x - 4y = 7

  [2]    x - 4y = -17

 [2]    x = 4y - 17

// Plug this in for variable  x  in equation [1]

  [1]    9•(4y-17) - 4y = 7

  [1]    32y = 160

// Solve equation [1] for the variable  y  

  [1]    32y = 160

  [1]    y = 5

// By now we know this much :

   x = 4y-17

   y = 5

// Use the  y  value to solve for  x  

   x = 4(5)-17 = 3

Step-by-step explanation:

9+4(7)

Step-by-step explanation:

Start by replaceing y with 7

Do the same with x

∈3,600

step-by-step explanation: