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put this solution on YOUR website!Let Number of pencils bought be 'x' and pens be 'y'.
Then 25x + 80y = 2000 ----- (1) and x + y = 36 ------- (2)
5x + 16y = 400 [Divide eq (1) with 5.]
5x + 5y = 180 [Multiply eq (2) with 5.]
11y = 220
y = 20
x + 20 = 36 [Use eq(1).]
x = 16
Therefore, Susan bought the number of pencils are 16.
And
Let the two numbers be 8x and 5x.
8x - 5x = 24
3x = 24
x = 8
Therefore, the numbers are 64 and 40.