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Step-by-step explanation:
Question 1
        x = 5            Equation l
        2x + y = 10        Equation ll
- Substitute Equation l in equation ll
        2(5) + y = 10
        y = 10 - 10
        y = 0
- Solution  (5, 0)
Question 2
         x + 16y = 20      Equation l
         x = 4y           Equation ll
Substitute equation ll in equation l
        4y + 16y = 20
            20y = 20
              y = 20/20
              y = 1
-Find x
        x = 4(1)
        x = 4
-Solution
        (4, 1)
Question 3
          2x + 8y = 20       Equation l
           x = 2            Equation ll
-Substitute equation ll in equation l
          2(2) + 8y = 20
           4 + 8y = 20
              8y = 20 - 4
              8y = 16
               y = 16/8
               y = 2
- Solution
          (2, 2)       Â